of the sea; moreover, in other localities the sea itself was coloured green. Captain Parry also mentions in the same latitudes the existence of a very great number of animalcules, which he designates under the name of Beroes, and which he says nourished themselves upon this green slime. These observations, although incomplete, must not be forgotten, and may be placed alongside those of Captain Ross, in the Antarctic regions. (To be continued.) Description of a new species of Echeneis (E. tropicus);—and of a new Lernean of the genus Penella (P. remoræ), infesting the Echeneis remora; with some remarks on the economy of the Remora. By ANDREW MURRAY, Edinburgh. The Echeneis or Remora, as most of our readers are aware, is a genus of small fishes which have a flat oval disk, composed of a number of transverse cartilaginous plates, on the top of their head, and so contrived as to act as a sucker, by which they attach themselves to larger fishes or vessels, and are carried about with them. They also occasionally attach themselves to rocks, more especially, it is said, during storms, when they would be unable otherwise to withstand the fury of the waves. The ancients had the most absurd fables regarding the species with which they were familiar (the Echeneis remora of the Mediterranean), all bearing some more or less recondite allusion to its supposed resisting or attracting powers. Philtres could be made from it capable of deadening and extinguishing the fires of love. It could stop the course of justice, and delay the procedure in the public tribunals. It could arrest miscarriages in females, and when preserved in salt, its mere approach brought from the deepest wells any gold which might have fallen in. But the grand power which it possessed, was to stop ships in full sail by attaching itself to them. Pliny, who tells the above stories, gives a most graphic and eloquent account of its powers in this way, which he supports by one or two anecdotes. It was an Echeneis that, at the battle of Actium, stopped Antony's vessel when he was going to survey the lines of his vessels, and encourage his adherents. "More recently," says he, "the ships bringing Caius, on his return from Andura to Antium, was stopped by an Echeneis. But his astonishment was not long when he saw that, of all his fleet, his galley alone did not advance. Those who went overboard to ascertain the cause, found an Echeneis sticking to the helm, and showed it to the prince, who was indignant that such an animal had been able to get the better of 400 rowers, and was very much surprised that this fish, which in the sea could keep back his vessel, had no longer any power when brought on board." Caius would seem not to have been quite free from doubts on the subject. It is long, however, since the Echeneis has lost all claim to such supernatural properties. It is now only known as a very interesting little fish provided with the sucking apparatus I have referred to, and most associated with the shark, so much so, as to be known by mariners under the name of the pilotfish, from its playing around and before it.* But it by no means confines itself to the shark. It attaches itself to almost any large fish that comes in its way. Yarrell records a specimen as having been taken in the British seas on the back of a cod, and it is frequently observed adhering to vessels. It usually swims upon its back, and from the under jaw being more projecting than the upper, and the colour of the upper and under surfaces being the same, one, at first sight, would imagine that the belly was the back, and that the disk was placed under the chin, instead of on the top of the head. The colour is a uniform deep olive-brown (except in the case of some albino varieties, which are wholly white); and Lacepede remarks, that the colour of the belly in this fish would seem to indicate that it was the less exposure to light which made the bellies of other fishes pale. - Four species of Echeneis have been described the E. remora, E. naucrates, E. osteochirus, and the E. lineatus. I have recently received from Old Calabar, through the kindness of my friend Mr Wylie, another species, which I propose to name E. tropicus. It approaches the Mediterranean species, E. remora, in its characters, and I think it by *The name pilot fish is now commonly applied to the Naucrates ductor, but it equally belongs to the species in question. See Lacépède, &c. no means improbable that, from its resemblance, it has hitherto been overlooked or confounded with that species. It will presently be seen, however, that its specific characters are sufficiently distinct. The character which has been most relied upon for distinguishing the species of Echeneis is the number of the plates in the disk on the head. For instance, the E. remora has a double row of eighteen plates, the E. naucrates of twentytwo, the E. osteochirus of twenty-seven, and the E. lineatus of six plates. The species which I have now to describe has a double row of seventeen plates. I believe this character to be constant, and susceptible of as little variation as the parts of the internal skeleton of the fish, or of the external skeleton of an articulated animal. Indeed, we may look upon these parts of the disk as dermal plates, and therefore as a modification of the external skeleton. It should follow, that wherever we find a difference in the number of the plates, we may be satisfied that there is also a difference in the species. Mr Yarrell seems not to have assigned a sufficient value to this character, for I find him in his "British Fishes" describing the E. remora as having seventeen or eighteen plates on the disk. I do not find Cuvier, or any other author, stating the number at anything but eighteen, nor in their descriptions do they give any latitude as to number. I have myself examined a good series of specimens of the E. remora, and I have never found an instance in which there were more or less than eighteen plates. I have no doubt, therefore, that Mr Yarrell has had the species I now describe through his hands, and that, finding the number of plates so close to that of the true E. remora, and the general appearance much resembling it, he has supposed it to be the same species, and thence concluded that the character in question was variable. The constancy of this character is the more important in this genus, that the formula of the fin rays to which ichthyologists are accustomed to trust, is so difficult of ascertainment, that it cannot well be relied on. The fins are covered with a thick untransparent leathery skin, which makes it very difficult to count the rays correctly. Almost invariably in counting them I have been in doubt whether I had not omitted one or two minute rays at the commencement or ending of the fin. Nothing but dissecNEW SERIES.-VOL. IV. NO. II.-OCTOBER 1856. T tion can allow a satisfactory enumeration of them. It is no doubt owing to this element of error that Cuvier and Yarrell give a different formula of the fin rays of E. remora. I do not think that either of them are quite correct, and I give the following comparison of the result come to by these authors and myself, to show the difficulty to which I allude: In giving this latitude in my enumeration, I do not mean to say that the number of rays varies from 20 to 21, 19 to 21, and 17 to 19, but simply that, from the causes above mentioned, I have been unable to make out, to my own satisfaction, which of these numbers is the correct one. With these observations on the specific characters of the genus, I shall now give the description of the new species, merely premising that some parts of it, more particularly those relative to the mouth and teeth, are equally applicable to the Echeneis remora. Had I found a detailed description of these parts in any account of the latter species, I would merely have referred to such description, but as I have not done so, and the structure of the mouth in both species is curious, I have given a more careful description of it. ECHENEIS TROPICUS. Head, from the symphysis of the lower jaw to the end of the operculum, very nearly one-fourth of the length of the whole body; if the tail is included, it is rather less that one-fourth. The tail is nearly two-thirds of the length of the head. The depth of the body, taken immediately behind the operculum, is nearly one-twelfth part of the whole fish, and continues about the same depth till it meets the tail. It is deepest just in front of the dorsal and anal fins, which both commence about the same distance from the head, but even there the depth is not quite a tenth of the whole length; the head is very much depressed and flattened, the body in the middle nearly round, and the tail compressed. The mouth is wide; the opening nearly horizontal, with an outer fringe of close-packed, even, and regular peculiarly-shaped teeth on the upper jaw. They are formed somewhat like the teeth of annelids, Fig. 1. the upper part They are not and are shown in fig. 1, where a side view is given of one tooth, and five are represented as seen in front. The upper half of the tooth looks like clear opaline enamel. They are pedunculated, and the peduncles stand quite apart, while at the teeth lie flat and close to each other. continued all the way back to the gape, but at the back part are replaced by a few scattered incurved teeth; within this outer fringe there is an irregular row of sharp teeth curved inwards behind this row, the teeth are irregularly placed two or three deep; another similar row of teeth surrounds. the front of the palate; the front and each side of the latter are broadly paved with a thick velvet-like packing of minute teeth curved inwards; its centre is free from teeth. The under jaw has an outer row of sharp teeth curved inwards, of a different shape from those in the outer fringe of the upper jaw. These teeth do not extend all the way back to the gape; within them there are four or five close-set irregular rows of small teeth; there is a small elongate diamond-shaped patch of minute velvet-like teeth, the same as on the palate, on the tip of the tongue. At the back part of the tongue the roots of the branchiæ (which are four in number) are seen to be furnished on each side with a curious dental apparatus opposed to the plate of teeth on the palate; and each tooth (if they can be called teeth) on the side of the branchial rays fits into the hollow between the two opposite ones on the next branchial ray. One or two patches of velvety teeth are situated also about the base of each branchial ray. The eye is large, placed about halfway between the symphysis of the upper jaw and the end of the operculum. The gill aperture is large. The adhesive disk is elongate, and nearly oval; it contains a double row of seventeen transverse cartilaginous laminæ, divided by a longitudinal mesial separation. The disk commences immediately behind the upper lip, and ex *The same arrangement occurs in the E. remora. Of it Yarrell says there is only one band of teeth in the upper jaw; but we see that there are two rows with several irregular interrupted rows following. |