PALEONTOLOGY OF NEW YORK. 



ventral edge and passing posteriorly with the same curvature. The postero- 

 ventral angle is broadly obtuse, the posterior margin .slightly incurved to the 

 liince-line. The surface is evenly convex and is ornamented by a series of 

 longitudinal carina', of which live, including the marginal ridge, extend the 

 entire length of the valve, four of them being prominently exsert at their 

 terminations upon the posterior margin. Intercalated between these carinse 

 is a series of shorter and less conspicuous ridges, beginning near the anterior 

 tremity and mostly confined to the cephalic region; one or two extend 

 for some distance upon the thorax. The number of ridges crossing the 

 cephalic region is eleven, one of the shorter of these crossing the eye-node. 

 The Bingle valve has a length of 23 mm., and a width of 10 mm. 



Dist ibution. Chemung group. In the shales near the summit of the forma- 

 tion, Warren, Warren county, Pennsylvania. 



Tropidocaris alternata. 



PLATE XXXI, FIGS. 14, 15. 



iikk. Ceratiocaridae from the Chemung and Waverly groups, etc. Second Geol. 

 Sun . Prima., vol. I'I'P, p. 19, pi ii. figs. 7 and 8. 1SS4. 



1 • Woi DWARDand Jones. Third Rept. Committee on Fossil Phyllopoda 

 ti !' Palaeozoic Rocks, p. 35. 1885. 



species is represented only by impressions of two somewhat fragmentary 



portions of left valves of the cephalothorax. Their outline cannot be satis- 



factorily determined, but indications show that is docs not widely differ from 



of Tropidocaris bicarinata. These fragments are characterized by the 



is longitudinal ridges extending apparently the entire length of the 



somewhal interrupted and irregular in the cephalic region. These 



» or carinae alternate in size, the best preserved specimen showing seven 



whirl, the larger are finely crenulate, but no other ornamentation is 



I on the valve. The eye-node is distinct and is crossed by the fourth 



or middle carina. 



W;r '"!>• I" the sandstones at Warren, Warren county, 



Ivania. 



