REPORT ON THE SFHENISCID^. 223 



times the length of the vertebral column as in Aptenodytes tceniatus, to eight or ten times 

 that length in AjJtenodijtes longirostris ; in the absence of any differentiation of the 

 syringeal from the adjoining tracheal rings ; in the mobility of the syringeal rings upon 

 one another ; in the cartilaginous condition of the syringeal rings ; in the amount of 

 displacement downwards of the vibrating membrane of the syrinx beyond the point 

 of bifurcation of the trachea ; and in the presence of a tracheal septum, which varies in 

 length from one-half in Aptenodytes toeniatus to three-fourths ©f that of the trachea in 

 Aptenodytes longirostris. 



If now we enquire whether any one of the characters above enumerated can, per se, 

 be regarded as distinctive of the genus Aptenodytes, as compared with other genera, I 

 reply that there are three which may be so regarded. These three generic characteristics 

 are to be ionnd.— firstly , in the form of the skull as a whole ; secondly, in the absence of 

 a complete coraeoidal foramen ; and thirdly, in the form and structure of the syrinx. 

 Given any one of the parts to which these remarks refer, and the identification of the 

 Penguin possessed thereof as a member of the genus Aptenodytes may at once be accepted 

 as proved. 



In the possession of every one of the above-mentioned characteristics, the two species 

 Aptenodytes longirostris and Aptenodytes tceniatus agree. At the same time the anatomical 

 investigation of these two birds shows that in their anatomy, as in their external con- 

 figuration, each is possessed of individual peculiarities which at once justifies us in 

 considering them to be distinct species, but species which belong to one and the same 

 genus. 



Turning now to the consideration of the characteristics of the genus Eudyptes, we find 

 that these are to be found in the oval form of the upper jaw, which is widest transversely 

 about the middle of its length, and tapers forwards and backwards ; in the relative 

 tenuity of the central bar of the upper jaw, which does not fiU up the interval between 

 the lateral bars ; in the elongated form of the anterior narial apertures, and the relation 

 which their posterior extremities bear to the lachrymo-nasal fossae ; in the stoutness and 

 lozenge-like form of the rami of the lower jaw bone ; in the great breadth of the supra- 

 orbital grooves, due to the presence of a supra-orbital ledge of bone which does not exist 

 in Aptenodytes, and is developed to a much less extent in Splieniscxcs ; in the moderate 

 development of the transverse temporal crest, which is more pronounced in Spheniscus 

 but scarcely exists in Aptenodytes ; in the coalescence of the upper end of that crest with 

 the cerebral portion of the cranium, and not with the cerebellar as in SpJieniscus ; in the 

 vertical direction and intermediate size of the post-orbital process, as compared with 

 that of Spheniscus and of Aptenodytes; in the strongly-pronounced curvature of the 

 zygomatic arch ; in the form of the scapula ; in the presence of a complete coraeoidal 

 foramen ; in the divergence of the lower end of the second from that of the thiixl 

 metatarsal bone ; in the relatively greater breadth and shortness of the tongue, as com- 



