182 PROCEEDINGS OP THE ACADEMY OF 



cile these conflicting views, and, if possible, to fix this question of 

 the genera with reasonable certitude, has been one object of the 

 present investigation. I found that any division of the species 

 according to the details of external form, as the size, shape, and 

 extent of feathering of the bill, length of tail, presence of peculiar 

 ptilosis, etc., would be, for the reason just alluded to, an elevation 

 of various characters, properly to be regarded as specific, to 

 generic rank ; while the ignoring of these would force me to the 

 other extreme of recognizing a single genus virtually equivalent 

 to the famil3 T itself. It seemed to me that, if there were true 

 genera among the penguins, the fact would appear from examina- 

 tion of internal structure ; and, having a number of skulls at com- 

 mand, I directed my attention to these. As far as my material 

 goes, the results of this investigation are to me highly satisfactory. 

 At the same time, having examined the skulls of only a limited 

 number of species, I cannot fix the generic status of all of them, 

 nor even say how far, if at all, the skulls of the species not ex- 

 amined may show inteygradation between the types of structure 

 herewith detailed. 



The skulls examined show three positively different patterns. 



A. The first is that presented by Aptenodytes pennantii. The 

 rostrum is much longer than the rest of the skull, attenuate, 

 particularly narrow and acuminate. The nasal opening is cor- 

 respondingly long and narrow. The upper prong of the nasal 

 bone is anclrylosed with the nasal prong of the prem axillary. The 

 palatines are anchylosed with the maxillae. The zygomata dip 

 downward moderately from the maxillo-jugal suture. The man- 

 dible is not abruptly deepened in any part of its length, and shows 

 a long narrow vacuhVy at the juncture of its symphyseal with the 

 succeeding elements. The angle of the mandible lies directly 

 below a perpendicular let fall from the mastoid. The interorbital 

 space on the top of the skull is broad and smooth, since the rough 

 depressions for the lodgment of the glands are narrow, and ter- 

 minate befoi'e reaching the anteorbital prominences. The tem- 

 poral fossae are very shallow, widely apart, and merely separated 

 by a slight bony ridge from the slight depression between them- 

 selves and the cerebellar protuberance. The greatest width of the 

 skull is one-third, or less, of its entire length. 



B. The second modification is afforded by the crested species 

 (Eudyptes proper). (PI. 4, fig. 1.) The rostrum is shorter or no 



