306 MR. W. K. PARKER ON THE OSTEOLOGY OF BAL/ENICEPS REX. 



by the lower plate of the vomer and by the palatines. The latter bones are kept apart 

 by the palatal plate of the vomer, but they have begun to form that tube-like prolonga- 

 tion of the posterior nares which attains its fullness in the Crocodile. In the Greeu 

 Turtle {Chelone mydas) the inferior vomerine plate reaches the pre-maxiilaries anteriorly, 

 thus keeping the maxillary palatal processes widely apart ; in this species the palatine 

 plate of the palate bone is not so well developed as in the Logger-head. In the smaller 

 Tortoises the descending portion of the vomer is less decidedly palatal, and we have 

 now before us the skull of a small Emys which has articulated to the sides of its vomer 

 a pair of ' turbinals,' which are evidently the proper homologues of the ethmoidal palatal 

 plates of Birds and of the turbinals of Lizards and Snakes. Professor Goodsir thinks 

 that the palatine plate of the vomer of Tortoises and Turtles always consists essentially 

 of these turbinal elements, which he names 'ethmoidal neurapophyses' {op. cit. p. 145). 

 The study of its development would prove or disprove this opinion. 



These small Chelonians with their feebly-developed and widely-separated ' palatines ' 

 lead us to the Lacertiajis and Ophidians, creatures that expose their double vomer on 

 the anterior palatine aspect of the skull, and have articulated to each moiety a very 

 perfect osseous ' turbinal,' which bone Professor Goodsir now (in these orders) considers 

 to be a mere exogenous outgrowth or cortical ossification of the ethmoid (p. 155). We 

 agree with him here, but not with his finding ' ethmoidal neurapophyses in the divided 

 vomer,' nor with his non-recognition of the actual homology of tiiese Lacertian and 

 Ophidian ' turbinals ' with those of the little Chelonian and of Birds generally. 



We now come to the structure of these parts in birds and mammals. The vomer of the 

 Goatsucker {Caprimulgus europceus), slightly grooved above and carinate below, appears 

 in the palate, between the inferior or palatine turbinals. In the Merlin {Falco (esalon) 

 these latter processes are anchylosed together, and form a large oblong mass behind the 

 palatine plate of the pre-maxillary, and between the laminar origins of the palatine 

 hones. The vomer, thin above and round below, articulates behind with the palatines, 

 being wedged between their ascending plates ; in front it descends and forms a lozenge- 

 shaped little block, notched in front and flat below, the inferior surface being quite 

 palatal. This descending anterior part wedges itself in between and behind the palatine 

 turbinals exactly as in the little Tortoise, supposing these bones not to have coalesced, 

 which they seldom do, the Merlin itself being somewhat exceptional in this respect even 

 among the Raptores. In the Rook, and in Corvine and Passerine birds generally, the broad 

 emarginate anterior end of the vomer descends, and appears in front of and between the 

 palatine turbinals. One more instance from the class of birds : — in the Albatros {Diomedea 

 exulans) we have an exception to the rule mentioned by Mr. Goodsir {op. cit. p. 159), 

 that the vomer is feeble when the palatines are large, and vice versd. In this large 

 palmiped the vomer is two inches and a half long, the palatines being relatively large. 

 Thin and laminar below, at its junction with the palatines, the vomer of the Albatros 

 diverges above into two very considerable laminae, whilst it is smoothly carinate below. 



