590 MORPHOLOGICAL METHOD AND RECENT PROGRESS IN ZOOLOGY. 



result of extreme specialization of a type common to all Sauropsida 

 with a "cellular" lung. The respiratory process in the bird may be 

 defined as transpulmonary, and it is an interesting coincidence that as 

 I write there comes to hand a memoir supporting Huxley's conclusion 

 and establishing the fact that there is a fundamental principle under- 

 lying the development and primary differentiation of all types of 

 vertebrate lung. 



The discovery of the Odontornithes in the American (Jretaceous is 

 so well known that it is ))at necessary to remark that nine genera and 

 some twenty species are recognized. To Arc/ueoj)te/'i/,r I shall return. 

 Before dismissing the Chelonia, however, it nuist be pointed out that 

 paleontology has detinitely clenched their supposed relationship to the 

 Plesiosaurs. Of all recent paleontological collections there are none 

 which, for care in collecting and skill in mounting, surpass the rep- 

 tilian remains from the English Jurassic (Oxford clay) now public in 

 our national uuiseum. The Plesiosaurs of this series nuist ])e seen to 

 be appreciated, and nothing short of a merciful Providence can have 

 interposed to insure the generic name Cnjptodeldux^ which one of 

 them has received, since the hiding of the clavicle, its diagnostic char- 

 acter, is an accomplished fact. It is due to secondary displacement 

 under the approximation in the middle line of a pair of proscapular 

 lobes, present in the Plesiosauria and Ciielonia alone, and until the 

 advent of this discovery misinterpreted. Taken in conjunction with 

 other characters of little less importance, conspicuously those of the 

 plastron and pelvis, this decides the question of affinity, and proves 

 the Chelonia to have had a lowly ancestr}", as has generally been 

 maintained. 



Recent research has fully recorded the facts of dexelopment of the 

 rare New Zealand reptile Sphenodon^ and it has more than justified 

 the conclusion that it is the sole survivor of an originally extensive 

 and primitive group, the Rhynchocephalia, as now understood. To 

 confine our attention to its skeleton, as that portion of its body which 

 can alone l)e compared with both th(^ living and extinct, it may ))e said 

 that positive proof has ))een for the first time obtained that the devel- 

 oping vertebral body of the terrestrial vertebrata passes through a 

 pair(Ml cai'tiiaginous stage and tliat in its (h^tails th(> latcu- dcvidopment 

 of this bod}" is most ncai'ly identical with that of the h)wcr Patrachia. 

 There has long Ix'cn a consensus of opinion tiiat the forward exten- 

 sion of th(> pt(>ryg()i(ls to meet the vomers in the middle line, known 

 hitherto in this animal and the crocodiles alone, is for the terrestrial 

 verte])rata a primitive character, and ]iroof of this has been obtained 

 by its ])resence in all tlu^ Rhynchocei)halia known. The same condi- 

 tion has also been found to exist in the IMesiosaurs, the Ichthyosaurs, 

 the Pterodactyles, the Dicy^nodontia, the Dinosaurs, and with modific*a- 

 tion in some chelonians. It has, moreover, been found in li\ing ])irds; 



