332 PROFESSOR OWEN ON THE SKELETON 



it is a compressed subquadrate plate, decreasing in length in the three succeeding 

 cervicals, in the last of which the parapophyses reappear as short horizontally extended 

 plates, the origins of which, approximating in the second dorsal, combine in the third to 

 form the lameiliform stem of a pair of diverging plates, which decrease in size in the 

 fourth with antero-posterior increase of the base of the stem, and in the fifth dorsal are 

 reduced to an expansion of the end of the stem, which now has reassumed the character 

 and position of a compressed lameUiform hypapophysis, which gradually diminishes to 

 the last dorsal'. In the sacrum it is represented by a hypapophysial ridge, which 

 subsides in the fourth of the coalesced series of vertebrae. 



In Alca impennis the lameUiform hypapophysis first appears on the tenth vertebra, is 

 reduced to a tubercle on the twelfth, and disappears on the thirteenth and fourteenth. 

 The fore part of the sacrum is carinate below in the Penguin, but not in the Garfowl. 

 The number of free caudal vertebrae is eight in the Penguin, eleven in the Garfowl. 



The cranial part of the skull is proportionally larger and longer in the Penguin ; it is 

 smooth and more convex above ; neither the temporal nor superorbital glandular depres- 

 sions meet at the mid line, and the temporal depression is narrower above, and is not 

 divided into an anterior and posterior facet as in the Garfowl. In Eudyptes chrysolo- 

 phus the glandular depressions are large, deep, and meet for a short extent anteriorly : 

 the temporal fossae are more than an inch apart on the calvariura. The cerebellar 

 prominence projects much further at the back' of the skull in the Penguin than in the 

 Garfowl. The paroccipital process is stronger than the mastoid, whilst in the Gar- 

 fowl they are equally developed. The condyles of the tympanic are bent more back, 

 the orbital process of this bone is relatively shorter, and the distal articular end is 

 narrower, in the Penguin. The pterygoids are more expanded anteriorly ; the palatines 

 are broader, and are convex below, in the Penguin, instead of being concave. 



The nasal bone retains its distinctness from the premaxillary and maxillary in the 

 Penguin, and has coalesced only with the frontal and prefrontal posteriorly ; its maxil- 

 lary prong is inclined more forward, at an acuter angle with the premaxillary prong, 

 than in the Garfowl, and it ends in a free point. The lacrymal is broader and longer, 

 reaching the malar below in the Penguin. The premaxillary is comparatively short 

 and rounded : the Penguins have a quite different type of beak from that in the Alcadw. 

 The malo-squamosal zygoma is sigmoidally bent, chiefly concave below, not straight as 

 in the Garfowl. The mandible retains as instructive marks of its primitive composi- 

 tion in the Penguin as in the Garfowl, and enables one to see that in the former the 

 surangular is relatively longer, the dentary shorter, but with its lower prong more pro- 

 duced posteriorly ; the angular is more produced behind the articular ; the rostral part 

 of the dentary corresponds in shape with the same part of the premaxillary, and differs 

 in the same degree from that of the Garfowl^. 



' Phil. Trans. 1851, pi. 52. figs. 48-51. 



' In Sula the basioccipital is impressed by a pair of large and deep ciicolar pits for the insertion of strong 



