66 PALEONTOLOGY OF liEW JERSEY. 



individual there appears on the posterior cardinal slope very faint indica- 

 tions of rather coarse radiating lines, but too faint to warrant the statement 

 that such markings really existed on the shell. 



These specimens were found in the collection of the Academy of 

 Natural Sciences, Philadelphia, marked "iJ£ ovata Gabb," and also marked 

 "types," but as they are totally distinct from the specimen figured as the 

 type by that author, and which is also now before me, I can only interpret 

 the error to some wrong identification at some subsequent time. The species 

 differs from M. ovata in its much greater size, more cylindrical as well as 

 more elongated form, prominently subangular umbonesand umbonal ridge, 

 strongly sulcated surface, and much broader anterior end. There is no Cre- 

 taceous species known with Avhich there is danger of confounding it. 



Formation and locality. — Tn the ferruginous clay beds of the Creta- 

 ceous in Burlington County, New Jersey, the special locality not mentioned, 

 but marked on the label as "middle beds," which I am led to believe incor- 

 rect from the fact of the lithological features of the specimens being exactly 

 similar to so many fossils from this same neighborhood which are credited 

 to the Lower Marls. 



Geuus LITHODOMUS Ciivier. 



There is a question among authors as to which of the two names 

 should be used. Lithodomus Cuv. or Litliophagus Bolt. The fact that the 

 latter is only a repetition of the specific name of the generic type is a great 

 objection, for which reason I have adopted the former. 



Lithodomus affiiiis. 



Plate XVII, Figs. 2 aii«l 3. 



Lithophagns affinis Gabb. Proc. A. NT. Sci., Pbil., 1S61, p. 124. Afeek, Check-list, p. IL 



Geol. Surv. K. J., 1868, p. 726. 

 L. Ripkyanm Gabb. Proc. A. N. S., Phil , 1876, p. 311. 



Mr. Gabb described this species from the tubes, or as I suppose the 

 filling of the tubes, and states tliat he had not seen the shell. In the col- 

 lection of the Academy of Natural Sciences, Philadelphia, there is an inter- 

 nal cast of a shell, somewhat imperfect at the posterior end, which is marked 

 with ink on the specimen " L. affinis type," which I suppose to have been the 



