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Show 1870.] DR. J. MURIE ON PHOCA GR03NLANDICA. 607 carefully executed drawings of the limb-myology oi P.fcetida. It is needless entering* into detail; but the result was that I detected no special arrangement in the muscles and tendinous distribution, both of the pectoral and pelvic extremities, which could satisfactorily account for the powers of grasp and differentiated raised creeping movements. In all three forms the flexor and extensor tendons agree in pattern and points of insertion. The small palmar and plantar muscles, including superficial and deep layers of interossei, are subdivided after the same fashion. As regards the shoulder and brachial muscles, there is no alteration in their implantation ; and hence no change in mode of action is apparent. If any specific difference exists, it must be in the volume and strength of the individual parts. But this is a factor which, unless very decided, the eye cannot well appreciate ; therefore to assume such is all that reasonably dare be ventured. Physiologically, it may be said there is more innervation ; but that can neither be seen, weighed, nor measured. I shall restrict m y notes of the internal anatomy to a single specimen, premising that the differences in the others examined by me were slight-chiefly relating to partial or deeper segmentation of the lungs and length of intestine. Meckel, in his ' Anat. Comp.,' merely incidentally alludes to P. grcenlandica, quoting the ' Naturhist. Bemerk. &c.,' of Thienemann ; but I regret I have not been able to lay hands on this latter work. In a young male which died of congestion of the brain the following admeasurements were taken by me:-Extreme length = 4feet3inches. Of this, regionally, from the edge of the upper lip to the occiput was 9^* inches ; from the occiput to the tip of the tail 3 4 | inches; from the occiput to the tip of the hind flipper 4 1 | inches; the free part of the fore flipper 7\ inches ; and the free portion of the hind limb 10| inches. The body weighed 41 lbs. ; the skin when removed 6 lbs. 2 oz., and the viscera, including the tongue &c, 5 lbs. 2 oz. ; the brain with its membranes and blood-vessels (the latter much congested), 8 ounces 2 drachms. In the specimen under consideration the heart presented a well-defined bifid extremity, the cleft being almost half an inch deep. The long diameter of the heart from root to apex was 3 inches, and the greatest transverse diameter near the base 3| inches. Others of the Greenland Seals did not show quite so deep an apical incision; but in all, traces of separation at the point were discernible. I infer that in Phoca grcenlandica, at a comparatively ripe age, nearly if not quite adult, this fcetal stage of heart-cleft obtains. But latitude must he given to such a premise; for 1 have observed once in a young Porpoise, Phoceena communis, with a length of body as great as the Seals, that a distinct division of the apex existed. In the Harp-seal this cardiac scission is very median in position, as in the Dugong and Manatee, and not so laterally placed as I found it in the Common Porpoise. The right lung was entire or without divisionary lobules; but the PROC. ZOOL. Soc-1870, No. XLL, |