G. B. Wieland — 'Zfpper Cretaceous Turtles. 185 



shown in figure 1. Several more or less isolated jaws of the 

 same form attain about double the size of that illustrated. 



The relative width of the lower jaw of Lytoloma is much 

 greater than in the living Chelonians. Its further peculiarities 

 are mainly to be observed in the dentalium, notable for its 

 remarkably long symphysis and very large pits for the inser- 

 tion of powerful masseter muscles. These specialized features 

 primarily suggest a conchifragous habit* The massive im- 

 perforate palatal surface described below also strongly supports 

 the view that these Lytolomas had become littoral conch-eaters, 

 finding their home and an abundant supply of mussels and other 

 " shell fish" on the New Jersey Cretaceous shore lines. 



The Cranium. 

 With the exception of L. (Eud&stes) platyops Cope no further 

 Lytoloma crania from the Upper Cretaceous of New Jersey 

 have been figured. The only specimen in 'the Yale collection 

 referable to the genus is an isolated anterior portion of a skull, 

 which is, however, in a wonderful state of preservation, as 

 shown in the accompanying text — figure 2 (A, B, and C). There 

 is no means of now determining with certainty whether or not 

 this specimen is a Lytoloma angusta. It is quite possible that the 

 lower jaw pertaining to it had a somewhat differently shaped 

 coronoid region than that of L. angusta. Rather than erect a 

 new species on such slender evidence, it may suffice to refer to 

 this rare and interesting specimen by number when comparing 

 its characters with those of other forms. With L. platyops 

 Copet this comparison is as follows : — 



Lytoloma (Euelastes) platyops Cope. Lytoloma, Yale specimen No. 91 3a. 



1. " Maxillaries and palatines sepa- 1. Maxillaries and palatines proba- 



rated throughout by the pro- bly separated throughout by 



longed vomer." elongate vomer. 



2. ' ; Posterior nares opposite palatal 2. Internal narial opening well back 



front margin of orbits " (? ?). from both the lower (palatal) 



and the upper (orbital) anterior 

 border of the palatines. 



3. ' ; Premaxillary margin project- 3. As in L. platyops; that is, pre- 



ing beak -like ;" alveolar face maxillaries projecting more 



little concave. than in the Chelonidae, but not 



forming a projecting and de- 

 curved beak as in either Chely- 

 dra or Archelon. 



4. "Vomer forming a central ridge." ; 4. Outer (or palatal) surface of 



vomer flat anteriorly but raised 

 between the palatines. 



5. Floor of nasal meatus perforate 5. Floor of nasal meatus imperforate 



for hook of mandible. and very thick. 



6. "Nostrils superior behind the 6. Asin L.Platyops(notBothremys). 



short projecting beak (not 

 borne on a projecting muzzle). " j 



* Dollo, Premiere Note sur les Cheloniens landenieus (eocene inferieur) de 

 la Belgique, Bull. Musee Roy. d'Hist. Nat. de Belg., t. iv, No. 3, p. 138, 1886. 

 + Loc. cit., p. 148. 



