624 REPORT— 1902. 



rationalised our knowledge of the avian lung and its sacs/'* was aware of the 

 fact that in our common Water-tortoise {Emys orbicularis), the lung is sharply 

 differentiated along the bronchial line into a postero-dorsal more cellular mass, an 

 antero-veutral more saccular, of which the posterior vesicle, in its extension and 

 bronchial relationships, strangely simulates the so-called abdominal sac of birds. 

 He had already instituted comparison with the Crocodiles,^' and was clearly coming 

 to the conclusion that the arrangement in the bird is but the result of extreme 

 specialisation 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 

 underlying the development and primary differentiation of all types of vertebrate 

 lung.""' 



The discovery of the Odontornithes in the American Cretaceous is so well 

 known, that it is but necessary to remark that nine genera and some twenty species 

 are recognised.''' To Archceoptenjx I shall return. Before dismissing the Chelonia, 

 however, it must be pointed out that palaeontology has definitely clenched their 

 supposed relationship to the Plesiosaurs. Of all recent palseontological collections 

 there are none which, for care in collecting and skill in mounting, surpass the 

 reptilian remains from the English Jurassic (Oxford Clay) now public in our 

 national museum.'^ The Plesiosaurs of this series must be seen to be appreciated, 

 and nothing short of a merciful Providence can have interposed to ensure the 

 generic name Cryptocleidus, which one of them has received, since the hiding of 

 the clavicle, its diagnostic character, 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 Chelonia 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 

 ancestry, as has generally been maintained.'''' 



Recent research has fully recorded the facts of development of the rare New 

 Zealand reptile Sjihenodon, and it has more than justified the conclusion that it is 

 the sole survivor of an originally extensive and primitive group, the Rhyncho- 

 cephalia, as now understood."^ To confine our attention to its skeleton, as that 

 portion of its body which can alone be compared with both the living and extinct, 

 it may be said that positive proof has been for the first time obtained that the 

 developing vertebral body of the terrestrial vertebrata passes through a paired 

 cartilaginous stage, and that in its details the later development of this body is 

 most nearly identical with that of the lower Batrachia.''- There has long been a 

 consensus of opinion that the forward extension of the pterygoids to meet the 

 vomers in the middle line, known hitherto in this animal and the crocodiles alone, 

 ia for the terrestrial Vertebrata a primitive character ; and proof of this has been 

 obtained by its presence in all the Rhynchocephalia known. The same condi- 

 tion has also been found to exist in the Plesiosaurs,"^ the Ichthyosaurs,"'' the 

 Pterodactyles,""' the Dicynodontia,' " the Dinosaurs,"' and with modification in some 

 Chelonians."** It has, moreover, been found in living birds ; ^'^ a most welcome fact, 

 since Arcliceoptery.v, in the possession of a plastron, carries the avian type a stage 

 lower than the Dinosaurs. It is pertinent here to remark that, inasmuch as in 

 tbose Dinosaurs (e.g., Compsognathus) in which the characters of the hind limbs are 

 most nearly avian, the pelvis, in respect to its pubis, is at the antipodes of that of 

 all known birds, and the fore limb is shortened in excess of that of Archceopteryx 

 itself, the long supposed dinosaurian ancestry for birds must be held in abeyance.™ 



Passing through the Rhynchocephalia to the Batrachia, we have to countenance 

 progress most definite in its results. The skull, the limbs and their girdles, are 

 chiefly concerned, and this in a very remarkable way. 



In the year 1881 there was made known by Professor Froriep, of Tiibingen, the 

 •discovery that the hypoglossus nerve of the embryo mammal is possessed of 

 dorsal ganglionated roots.'' Again and again have I heard Huxley insist on the 

 fact that the ventral roots of this nerve are serial with the spinal set, but never did 



