een ye ea E ga ie Ea PRR eg eee ee Py 
re REM À 
1885.] Embryology. 1013- 
sixths to three and one-half inches long the whole of the chon- 
drocranium, with its visceral arches, has become sauropsidan, 
and the investing bones are quite crocodilian in number and rela- 
tion. The chondrocranium is better developed than in any 
existing reptile or bird. The mandibular arch in the crocodile is 
the culmination of the oviparous type. In the early stages the 
mandibular suspensorium is extremely like that of the more gen- 
eralized selachians. There is a distinct suprastapedial element in 
the hyoid arch. 
Birds.—The “cape wigeon ” of Latham, and Anas capensis of 
Gmelin, is noted by T. Salvadori as occurring in Shoa. It is re- 
described as Querguedula capensis —Mr. R. B. Sharpe describes 
an apparently new nuthatch (Sz¢/a whiteheadi) from the mountains 
of Corsica. 
EMBRYOLOGY.! 
ON THE GENESIS OF THE EXTRA TERMINAL PHALANGES IN THE 
Creracea.?—In what manner the extra terminal phalanges of the 
second, third and fourth digits of the manus of such a type as 
Globiocephalus amongst Cetaceans, was evolved, has been a 
question which my studies gave little hope of satisfactorily an- 
swering until I had noticed that the bony digits of both the 
manus and pes in the pinnipeds are prolonged into the flat ter- 
minal integuments of the limbs far beyond the nails as unseg- 
mented bars of cartilage, which are really unossified extensions 
of the ungual phalanges. The nails are borne upon the dorsal 
aspect of the ungual phalanges in pinnipeds, the ossified shafts of 
these phalanges usually ending abruptly to be continued into the 
terminal bars of cartilage. In Histriophoca the terminal cartilag- 
inous extension of the last joints of the digits are quite rudimen- 
tary, but the point where the ungual phalanges abut distally upon 
the terminal cartilages is still visibly marked in this species. In 
the walrus, the fur-seal and sea-lion the terminal cartilages of the 
igits are more developed, and articulate directly with the ab- 
ruptly truncated ends of the ungual phalanges, In the manatee 
the ungual phalanges of the manus terminate abruptly ; that they 
support cartilaginous extensions of notable length seems improb- 
able. The terminal cartilages of the digit apparently reach their 
greatest or strongest development in the walrus. 
The foregoing data when interpreted by the aid of embryolog- 
ical theory, as actually observed to hold in other forms, and linked 
with the explanations afforded by other facts which will be given 
later on, will, it seems to the writer, gives us a rational hypothe- — 
sis of the origin of the extra-terminal digits in the manus of the 
ee 
whales. 
Edited by Joun A. RYDER, Smithsonian Institution, Washington, D.C. ; 
This note presents the substance of conclusions reached by me in my memoir en- 
titled, «On the development of the Cetacea, together with a consideration of the 
Probable homologies of the flukes of cetaceans and sirenians,’’ now in press 
