SEAL-EilP.RYOS. 1 7 



would not liavo cxpecteil is that, iu spite of the presence ol a large liver, the right 

 lunfj extends liaekwards to a greater distance than does the left, thus giving the right 

 lung a greater antcro-posterior, as well as a greater transverse diameter. A small 

 lolus- impar was present connected with the root of the right lung. 

 In .specimen No. 24 the actual measurements were — 



Greater antero-posterior length — right lung . 88 '5 mm. 



(ireater anteroposterior length — left lung. . . 85 '3 mm. 



Circulatory System. 

 As in the case of the other systems, the anatomy <jf the circulatory system of the 

 Pinnipedia has been so fully and carefully described by Dr. Murie [loc. cit.) that there 

 remains but little to add, and I shall content myself by referring merely to a few 

 points which have either been omitted by that author, or which I wish to accentuate. 



The heart appears to be somewhat disproportionately broad, being mainly due 

 to the breadth of the right ventricle. The heart iu specimen No. 24 furni.shes the 

 following mea.surements : — 



Total maximum breadtli ... 55 mm. 



Total maximum length ... 50 mm. 



Ivight ventricle breadth . . . 35 mm. 



Right ventricle length . . . . 50 mm. 



Left ventricle breadth .... 20 mm. 



Left ventricle length . . . .35 nmi. 



The apex is traversely blunted, with a distinct notch separating the apices of the 

 two ventricles. There is nothing in the interior of the heart requiring special mention 

 beyond the fact that there is a well-marked moderator band. 



From the arch of the aorta spring three arterial trunks, an innominate, a 

 left carotid, and a left subclavian, as ]\Iurie has shown to be the case in the Otariidie 

 but not in the Trichechidse. • Thero is but a single renal artery to each multilobular 

 kidney. With regard to the middle sacral artery, around the morphology of which 

 so much discu.ssion has centred, I failed to discover, even in quite young specimens, 

 any evidence of a primitive double nature. So far as I was able to determine, this 

 artery was distinctly a median continuation of the dorsal aorta arising at the point of 

 bifurcation, perhaps slightly from the dorsal aspect. In one foetus (No. 24) the 

 middle sacral took origin from the dorsal aspect of the right common iliac artery, just 

 at its commencement ; I could find no corresponding lirunrh ari.sing from the left 

 common iliac. 



The middle .sacral itself, -as one would expect from the very reduced size of the 

 tail, is an exceedingly slender ves.sel. Aljout the distance of a couple of vertebrai from 

 the point of origin it gives off a pair of bilaterally symmetrical branches which have 

 all the appearance of ordinary segmental arteries. 



VOL. V. D 



