400 MR. A. H. G. DORAN ON THE MORPHOLOGY 



and proportionally small dimensions. The ear-bones of an adult Otaria jubata are very- 

 much smaller than those of any small Seal, such as Phoca hispida. 



The malleus from the skull of a Sea-lion (Otaria stelleri) (PI. LIX. fig. 20) that 

 measured 0-305 metre from the prsemaxilla to the front of the foramen magnum, is itself 

 only 0-008 metre in length from the summit of the head to the tip of the manubrium ; 

 but this and the other ossicles, though small in these eared-seals, are always of stout 

 make. The head of the malleus, instead of projecting well above the articular surface, 

 as in Man, or forming a smooth convexity in front of it, as in most of the Pissipedia, is 

 hollowed out anterior to that surface, and forms a shallow pit as in all other Pinnipedia. 

 The articular surface is very wide laterally and rather narrower vertically ; each facet has 

 so high a vertical convex ridge meeting its fellow that the whole area is quite convex, 

 forming a prominent angle in a horizontal view, though, viewed perpendicularly, the 

 planes of the facets do slope towards each other, and form a distinct concavity. The 

 groove dividing these prominent facets is but faintly marked. The neck is thin, 

 much constricted towards the manubrium, and never long. The manubrium is longer 

 than in the true Seals, and shorter than in the Pissipedia ; it is broad, and flattened 

 laterally at the base, narrowing laterally, and turning well up at the point, which is only 

 slightly spatulate ; it does not curve as in the Dog and Hysena. There is a sharp angle 

 at its base ; and its outer aspect forms a true well-bordered surface, very narrow, except 

 at the base and at the slight dilatation near the extremity There is no trace of a pro- 

 cessus muscularis, nor of any lamina, the processus gracilis running close under the 

 head and neck, to which it is fused by a medium of very compact, not lamellar, bone. 

 All the characters of the Otarian malleus are thoroughly phocine, putting aside its 

 small dimensions. "Yet Hyrtl says, — " Bei Otaria ist er (der Hammer) nicht grosser als 

 bei der Pischotter, und hat den gemeinsamen Typus aller Pleischfresser." Had that 

 distinguished anatomist said " common type of all aquatic Carnivora," he would have 

 been correct ; but he means the reverse, as the context shows. 



But the incus does not approach any of the singular forms observed in the other 

 Pissipedia. It assumes very much the form seen in Man, though smaller in proportion 

 to the malleus, having high compressed sides, a rather short, but stout, blunt-pointed 

 and only slightly divergent processus brevis, and a long, slender, far-stretching stapedial 

 crus. This is a modification of the forms' seen in the arctoid Carnivora (compare figs. 49 

 & 50, PL LVIIL), where the posterior crus is short and not divergent. The extended or 

 widely divergent character of the processus longus is, it will be remembered, very 

 marked in TJrsus maritimus, in JElurus, and to a less extent in Bassaris. The little 

 stapes has stout crura, often, but not invariably, fused ; they are not inserted precisely 

 into the extremities of the base, which is very thick, and quite concave horizontally. 



In Otaria jubata the ossicula are largest : the incus is as large as in Homo, and similar 

 in form ; the posterior part is much higher than the front of the body ; the sides are 

 almost flat. The whole bone is wonderfully light in make compared with the incus in some 

 true Seals. 



In Otaria stelleri (PI. LIX. fig. 20) the concavity on the front of the head of the 

 malleus is very shallow, the neck and manubrium are moderately long ; the posterior part 



