966 MI?. \v. p. PYCRAFr ON THE [Dec. l;3, 



A. forsteri has a conspicuous downward curve, that of A. patn- 

 f/onica is nearly straight. The posterior dentary border resembles 

 that of Py(/03celis. The inferior border of the supra-angular is 

 gently curved, not notched as in Pygoscdis. The splenial is long 

 and narrow, and does not close the vacuity left by the excavation 

 of the dentary and supra-angular sutures. The coronoid in 

 A. patagontca is short and truncate anteriorly ; in A. forsteri it is 

 very long and slender, running forwards as far as the middle of 

 the anterior lateral vacuity. 



In Spheniscus the jaw is deeper from the middle of the supra- 

 augular to the posterior border of the anguiare than in Pygoscelis, 

 and the processus anguiare is longer. The anterior lateral vacuity 

 is completely closed by the splenial. The coronoid is triangular 

 in form : its inferior border is closely applied to the supero- 

 posterior boi-der of the splenial. 



EudypUda, in the form of the lower jaw, closely resembles 

 Spheniscus, but is more slender throughout, and the internal and 

 posterior angular processes are short, rather resembling those of 

 Pygoscelis. It can easily be distinguished from Pyguscelis, however, 

 by its shorter coronoid. 



The Hyoid. — The hyoid of the Penguins resembles that of 

 the Tubinares much more closely than that of the Pygopodes. The 

 basibranchial, seen from above, is more or less shield-shaped, and 

 is produced anteriorly into a short blunt process, bent almost at 

 right angles to the main axis, and posteriorly into a similar process, 

 but in the same plane as the body of the bone. The anterior 

 process supports a cartilaginous basihyal, the posterior supports 

 the urohyal. The urobyal is entirely cartilaginous and rod-shaped. 

 The ceratobranchials are separated one from another at the base hy 

 the median posterior process ; each is about 3 times as long as the 

 basibranchial ; the epibranchial is about i the length of the cerato- 

 brauchial, from which it is separated by a cartilaginous rod rather less 

 than \ length of the epibranchial itself. 



The Cranicd Cavity. — The metencephalic fossa is well defined. 

 Its floor is flattened, and continued backwards, rising gently mean- 

 while to the free edge of the occipital condyle. It rises gently at 

 the sides. The vagus foramen pierces its posterior lateral margin, 

 and to the inner side of this lie two small condyloid foramina for the 

 xii. nerve. The internal auditory meatus lies immediately above the 

 vagus foramen, in the body of the prootic. Anteriorly, the fossa 

 rises somewhat abruptly and overhangs the pituitary fossa, forming 

 the dorsum sellae. 



The cerebellar fossa is bounded by the supra-occipital and 

 parietal behind and above, the pro- and epiotic laterally, and the 

 dorsal rim of the foramen magnum behind. A low tentorial 

 ridge cuts it off in front : ventrally it merges with the meten- 

 cephalic fossa. The floccular fossa lying between the epi- and 

 prootic is large and deep. 



The mesencephahc fossa lies in the alisphenoid. The ventral 

 portion of the tentorial ridge bounds it externally, the prootic and 



