358 PROF. G. B. HOWES ON HATTERIA. [May 6, 



original specimen (Bullet. Mus. Belg. t. ii. p. 185), and as doubts 

 had recently been thrown upon its existence by Cornet and Smets 

 (c/. Dollo, Zoolog. Jahrb. Jena, t. iii. Anat. p. 433), he deemed it 

 advisable to examine the material at his disposal. Six spirit-specimens 

 were accordingly examined ; five of them shovced that, as with the 

 examples of Banr (Zoolog. Anz. 1886, p. 1) and Dollo, the "pro- 

 atlas" was present and bilaterally symmetrical, while in the sixth 

 (viii.) it was present on tlie right side only, having been apparently 

 removed on the left. He fully acquiesced in Dolio's criticisms of 

 the statements made by Cornet and Smets and of the views of these 

 and other observers, and agreed with them in regarding the " pro- 

 atlas" as (I.e. p. 437) "without doubt constant in Hatteria" ; 

 he, moreover, believed that it was invariably present on both sides, 

 and that in tliose examples in which it had been detected on one 

 side only, it had been either lost (as suggested by Albrecht, /. c. 

 p. 192) in maceration, or incautiously removed. Referring to the 

 general relationships and morphology of the " pro-atlas," he pointed 

 out that the former are most nearly in harmony with the supposition 

 that it represents the arches of a vestigial vertebra. It articulates 

 upon the skull ; and in its relations to the episkeletal muscles it 

 repeats the conditions of the atlas ; its arches are preformed in carti- 

 lage (cf. Baur, Amer. Nat. 18S6, p. 288); they lie, like those of a 

 normal vertebra, buried in the dorso-lateral (occipito-atlantal) liga- 

 ments (fig. 3) of the vertebral column, and their separation in the 

 dorsal middle line is but an exaggeration of that so characteristic of 

 the atlas in Hatteria, Crocodilia, and many either Sauropsida. He 

 stated that he was inclined to accept Dolio's declaration of homology 

 between those various structures, which have been described in leading 

 classes of Vertebrata, to which he collectively applies the term " pro- 

 atlas" (for genera and species see Dollo, Bull. Mus. Belg. t. iii. 

 p. 127, and Zoolog. Jahrb. I.e.); and that the views of that author 

 appeared to him to be in complete harmony with Froriep's important 

 discovery (Archiv f. Anat. u. Phys., Anat. Abth. 1882, p. 279) of 

 the vertebral nature of the occipital segment of the skull, and with 

 those of Sagemahl (Morpholg. Jahrb. Bd. ix. p. 177), Jungersen, 

 and others which bear upon it. 



Vomerine Teeth. — These were originally described by Baur (Zool. 

 Anz. 1888, p. 85) in a young individual of 210 millim. total length, 

 the skeleton of which was still largely cartilaginous. Prof. Howes's 

 interest in the question had been heightened by a statement of Mr. 

 Boulenger's to the effect that he had not been able to find vomerine 

 teeth in any of the skulls of Hatteria in the Natural History Museum. 

 He had examined the palates, in all, of nine specimens, details of 

 which were given as follows : — 



Specimens examined. 



Prepared skeletons. 



I" Pro-atlas " Vomerine teeth 

 absent. 

 present, the right the larger. 



