THE LOWER GREENSYND OF NEW ZEALAND. 329 



as there is between the New-Zealand form (fig. 5) and the original 

 type specimen of /. brevirostris (fig. 4). 



Callorhynchus* Hectori, nov. sp. (PL XXI. figs. 0-9.) 



The second Chimoaroid jaw, alluded to above as having been 

 brought from New Zealand by Dr. Hector, is a small right maxilla 

 winch presents certain peculiar and interesting characters. 



This maxilla measures little more than an inch in length, and not 

 more than three fourths of an inch in width at its widest part. The 

 oral surface of the specimen is exposed, the upper portion being 

 imbedded in the matrix. The entire bone is much depressed, as 

 show r u in figs. 8 & 9 ; and this is evidently its natural form, for 

 there is not the slightest evidence of its having been distorted in 

 the process of fossilization. It is narrowest in front, and widens out 

 at the hinder part, the outer angle being produced backwards, 

 downwards, and outwards, so as to form a conspicuous process. The 

 oral surface is provided w T ith but one tooth, composed of the tubular 

 kind of dentinal substance ; this one, however, has a peculiar 

 form. Posteriorly the tooth appears to pass into the substance of 

 the bone, as in the other forms of the Edaphodontidae ; and at this 

 part it is proportionally wide, occupying the greater part of the 

 width of tho bone ; passing forwards it is seen, at a distance of about 

 | of an inch from its hinder border, to separate into two processes : 

 one of these passes along the inner side near the symphysis, almost 

 to the anterior end of the maxilla ; the other extends along the outer 

 margin for some little distance, but does not reach so far forward as 

 the inner one. Between these two processes there is a depressed 

 space, the inner process standing up in relief as a rounded ridge. 

 Both sides of each of these processes appear to have been w r orn by 

 attrition against the teeth of the mandible. Judging from the man- 

 ner in which this maxillary tooth is worn, it seems at first sight that 

 there must have been at least three teeth in the mandible — one to 

 cut out the central groove in the maxillary tooth, and a second and 

 a third to wear away the inner and the outer sides. But a study of 

 the recent Callorhynchus shows that the mandible was probably pro- 

 vided with but one tooth. 



It will be remembered that the maxilla of Edaphodon is charac- 

 terized by three teeth, that of Ischyodus by four, and that of Elas- 

 modus by possessing two elongated teeth and a series of dental 

 laminae upon the outer margin. In the young condition it appears 

 that the two long teeth are joined posteriorly and rolled in a pecu- 

 liar scroll-like manner. In general appearance this tooth resembles 

 that of the New-Zealand maxilla (compare PI. XXI. fig. 6 with 



* When the paper was read before the Society, this specimen was described 

 as the type of a new genus under the name of Upsilodus ; but some remarks 

 made by the referee induced me to reexamine the matter. Through the 

 kindness of Dr. Griinther, I have had the advantage of studying the recent 

 Callorhynchus antarcticus, and have convinced myself that there are no such 

 important differences between its maxilla and this fossil as, from descriptions 

 alone. I had supposed to exist. I have therefore felt compelled to refer the 

 fossil maxilla to CCiVorhynchus. 



