16 PROCEEDINGS OF THE ACADEMY OP 



dense layer without or within. This point alone distinguishes 

 the form from any found in the cretaceous strata. The external 

 surface of the carapace is smooth, and without trace of sutural 

 grooves of the horny scuta. The carapace is very thick, more so 

 than in any species of the order known, except the Agomphus 

 firmus. 



Measurements. M. 



Width of nuchal between antero-external angles (above) 0.2'25 

 Length do. three inches to right of middle . . . .11 



Thickness 02 



Thickness first marginal .30 



The length of the carapace, if proportioned to the size of the 

 nuchal bone, as in Ghelydra serpentina, would be forty inches, 

 with the width nearly the same. If the length of head and tail 

 were relatively less than in that species, and more than in the 

 species of Chelone, the total length would have been seven and 

 one-half feet. 



Of the affinities of the genus little can be said. The characters 

 of the plastron, as I noted when describing the genus, are more 

 those of Ghelydra than Chelone, and the present specimen adds 

 to the weight of the conclusion. The extensive union of the first 

 marginal and nuchal, and of the same with the first costal, are 

 very different from G'helone. The character of the sutures is 

 equally distinct from ain'thing seen in Ghelydra. 



As compared with L. polemicus, the present reptile is thicker 

 and probably considerably larger. The plastron is usually equal 

 to or thicker than the carapace in tortoises. In the present animal 

 the carapace is much thicker than the plastron of L. polemicus. 

 From Farmingdale, Monmouth County, N. J., from the pits of 

 the Freehold and Squankum Marl Company. Presented \>y the 

 attention of A. J. Smith, director. 



LEMBONAX INSULAKIS, Cope, sp. nov. 



Established on marginal and nuchal bones of a specimen from 

 the Eocene bed of Vincenttown. The first marginal forms a pro- 

 minent marginal angle, the sutures of the nuchal and second 

 marginal approaching each other at a strong angle. The margin 

 of the nuchal is continuous with the transverse edo;e of the ad- 

 joining marginal, and has not bordered it on the free side for any 

 distance, as is striking in L. popylaeus. There has evidently 



[April 10, 



