passes in front of this tooth, it is therefore the first molar; 2d, smaller than first, shorter, conical, and pointed forwards; 3d, rather larger than second, conical. (True, 3.) 4th, two external and two internal tubercles, nearly equal in size; the internal rather the largest; 5th, two external; and two internal and rather larger tubercles; 6th, two external; and two internal tubercles, nearly equal, and less defined; with another smaller tubercle behind. Length of Body, from muzzle to point of tail, 10 inches; tail, an inch, including fur, an inch. ANTERIOR LIMBS : Length of Arm 24 inches; Fore-Arm, not including hand, 24 inches. Hand.-The first phalanges of the fingers are covered and conjoined by the integuments of the hand, the two distal bones being the only oues that are free; length from wrist to point of fourth or longest finger, 14 inch. Length of Thumb, or First Finger, from wrist, ths of an inch of this, there is a free extremity of an inch in length. Length of Index or Second Finger.-Metacarpal bone of index finger measures ths of an inch in length. The first phalanx measures ths of an inch, and the distal phalanx ths of an inch. The ths of an inch; the th of an inch in length; the metacarpal bone of index finger and first phalanx being, together, the length of the metacarpal bone of the second finger. The metacarpal bones of the other fingers measuring about ths of an inch in length. Free extremity of finger about th of an inch. Length of Third Finger from wrist, first phalanx of third finger measures second phalanx less than ths of an inch; and the distal one rather less thanths of an inch. Free extremity is of an inch. Length of Fourth Finger from wrist, 1 of an inch. The first phalanx is nearly ths of an inch long; the second, ths of an inch; and the third, about ths of an inch. Fourth finger longest, free extremity an inch in length. Fifth Finger.—Length from wrist 1 inch. The first phalanx is about ths of an inch in length; the second, ths of an inch; and the third about ths of an inch. Free extremity ths of an inch. SPAN, 1 inch andths of an inch. POSTERIOR LIMBS: Length of Thigh, 2 inches; of Leg, 2 inches. Foot, from ankle-joint to point of longest finger or toe-the fourth, 1 inch. Tarsus, not elongated, about an inch in length. Metatarsal bones measure from ths to ths of an inch in length. The first phalanges (with the exception of the thumb), like those of the hand, are conjoined together. Thumb or First Finger.-Thumb with metatarsal bone, about ths of an inch long. First phalanx, ths of an inch; second, ths of an inch. Length of Second Finger, 1 inch; first phalanx, nearly ths of an inch; second phalanx, ths of an inch; third phalanx, bone of claw, ths of an inch; claw itself, ths of an inch. Free extremity, an inch. Length of Third Finger, first phalanx, ths of an inch; second phalanx, ths of an inch; third phalanx, ths of an inch; third finger smaller than the fifth, and free about ths of an inch. Length of Fourth Finger, first phalanx, ths of an inch; second phalanx, gths of an inch; third phalanx, inch; fourth finger longest, free about Length of Fifth Finger, first phalanx, second phalanx, ths of an an inch. ths of an inch; ths of an inch; third phalanx, nearly ths of an inch. Larger than third finger, being intermediate between it and the fourth, and free for about ths of an inch. SPAN measures nearly 2 inches in length. This animal possesses a clavicle. The stomach is moderate. in size, and rounded in form, and contained what seemed to be digested vegetable matters. It has a large sacculated cœcum of about 13ths inch in length. MICROSCOPIC STRUCTURE OF THE HAIR OF ANGWANTIBO.It occurred to me to examine through the microscope some of the hairs of this little animal; and I was much struck by their apparent variety and beautiful cellular structure. Plucking a few at random from the upper surface of the body, I found I had got three different varieties: large flattened hairs, showing a combined series of cells; smaller hairs, containing a single series of cells; and each displaying the external or epithelial coating of the hair, which forms a series of overlapping margins or scales, their free edges being directed towards the points of the hair; and, lastly, small bent or curved solid horny-like hairs, with this overlapping external coating developed here and there into large hook-like processes or spines. At my request, my friend Dr T. Strethill Wright made a minute microscopical examination of these hairs, and sketched the accompanying careful drawings (see Plate VIII.), which show very well their beautiful structure. Dr Wright used simply water in examining some of the hair; and this fluid entering by the cut extremities, and permeating the hair thoroughly, distinctly revived and exhibited their internal cell structure. In the smaller-sized hair, containing only one series of cells, the cells are found to have an hourglass contraction in the middle, the lower half of the cell containing the colouring-matter of the hair, and the upper part of the cell displaying a distinct central nucleus, the existence of which, at least in the body of the hair, is a fact which was new to both of us, if not altogether new to microscopists in general? These nuclei were also beautifully seen in the cells of the larger hairs. Dr Wright has figured (Plate VIII. fig. 4) the peculiar appearance which some of the hairs displayed, of black bars, arranged in a somewhat parallel manner, or zigzagging from one extremity to the other, in the central portions of the bodies of the hair; for the lower, and upper portions of all the hairs, showed no cell cavities, being formed apparently of solid structure. These black bands were due to some of the uncut hairs being mounted in turpentine or balsam, which did not permeate the hair like the water, but obscured their true structure altogether, by enclosing the air as a black band, which was varied both in shape and in contiguity, in the lacerated cells of the hair. Thick hair or fur of a cellular structure containing thus enclosed a considerable amount of atmospheric air, a bad conductor of heat, and therefore useful in preventing the rapid cooling of the body of the animal, has been believed to be peculiarly adapted as a covering for animals inhabiting cold climates; it seems, however, to be not inappropriately found on this little animal, which is stated to search for its food by night, and is therefore exposed to the damp and cold which occur at night in even a tropical forest. Annexed is Dr Wright's detailed description of Plate VIII. DESCRIPTION OF PLATE VIII. Fig. 1. Proximal portion of small hair in water, showing the recurrent spines. 2. Middle portion of small hair in water, showing hour-glass-shaped cells, 3. Summit or solid portion of large hair, showing contracted scales. 5. Middle or broadest part of large flat hair in water, showing single The Society may think I have entered rather too much into minute details of description. My reason for doing so, is to leave no doubt on the mind of any one, who may wish to make comparisons between this Angwántibo and any other individual of the genus, as to the special animal I have attempted to describe; and, for preservation, it is my intention to deposit the specimen in the Natural History Museum of the University. Since the preceding pages were in type (various unavoidable circumstances having delayed the publication of these Proceedings), I have been fortunate enough to get this specimen of the Angwántibo, and my detailed description, compared with the Potto described by Mr Bennett; and also with other specimens of the Potto in the collections of the British Museummy friend, Mr William Carruthers, of the Botanical Department of that great national institution, having, at my request, kindly taken the trouble of examining them. Mr Carruthers informs me I am correct in my opinion of the Angwántibo being a distinct species from the Potto, the Perodicticus Geoffroyi of Bennett; and also that it is a species apparently unknown to naturalists. I am therefore at liberty. to designate it the Perodicticus Calabarensis. Mr Carruthers says:" It is certainly a second species of Perodicticus. I compared it with two stuffed specimens of the Potto, and, with the assistance of Dr Gray, determined that it was new, differing chiefly from P. Geoffroyi in its tuberclelike tail and large ears. I also got Mr Bennett's specimen of the Potto,-which is yet fortunately in spirits,-and have been able more completely to discriminate the differences." At my desire, Mr Carruthers got an artist to make sketches of the head of Mr Bennett's specimen of the Potto, and also of my specimen of the Angwántibo, to show the various differences between them, in a more manifest way than by any lengthened description; and as both the specimens have been preserved in spirits, these comparative differences are seen at a glance, no change in the original appearance of either, having been made by any attempt at skinning, or otherwise preparing them for preservation. The sketches are of the natural size, and Mr Carruthers mentions they are very accurate, and are drawn without any attempt to put the hair in its natural position. In this way two things are gained. First, both specimens are exhibited as they really are, without any exercise of the imagination of the draughtsman; and, secondly, the outline of the skull is given in both, which is of much more importance than the outline of the hair, in animals where the hair is thick and stands nearly erect. The annexed woodcut (fig. 3), is the sketch of the head of the Angwantibo, the other (fig. 4), that of Mr Bennett's specimen of the Potto. |