CRUSTACEA. 20] 



abdominal cleft rapidly divergent. The surface is ornamented with concentric 

 lines or ridges as in the associated species. 



This species differs from Dipterocaris Procne in its more abrupt anterior mar- 

 ginal curvature, more anterior isthmus and the greater relative length of the 

 abdominal cleft. The dimensions of the specimen are 50 mm. in length and 

 18 mm. in width to the axial line. 



Distribution. Portage group. In the upper sandstones at Canadice, Ontario 

 county. 



Dipterocaris Procne. 



PLATE XXXV, F1US .'.VJ7. 



Dipterocaris Procne, Clarke. Amer. Jour. Sri. Mir,-. Third Series, vol. xxv. p. 122, figs. 2 and :i. IS83, 



Dipterocaris Procne, Jokes and Woodward. Geol. Mag-., Dec. iii, vol. i. No. s. p. 349. 1884. 



JHpteroearis Procne, Etheridge, W ward and Jokes. S nd Rejit. Committee on Fossil Phyllopoda of 



the Palseozoic Rocks, p 11. 1884. 

 Dipterocaris Procne, Etheridge, Woodward and Jones. Third Rept. Committee on Fossil Phyllopoda of 



the Palaeozoic Rocks, p. ;•>. 1S85. 



Carapace ovate or sub-quadrate in general outline. Surface normally elevated 

 along the dorsum and broadly rounding to the sides. Cephalic cleft very 

 broad and short, extending one-fourth the length of the shield ; abdominal 

 cleft narrower and longer. The isthmus or the area of the union of the alee is 

 situated somewhat anteriorly and has a length less than one-third the length 

 of the carapace. The angles made by the margins of the anterior cleft and 

 the periphery are large and obtuse, the posterior angles sharper. 



Surface ornamented by regularly concentric lines or ridges which make a 

 slight retral bend at the margins of the cleft. An uncompressed individual 

 has a length of 25 mm., and a width of 19 mm. 



Distribution. Portage group. In the upper portion of the formation in the 

 township of Canadice, Ontario county, and in the sandstones of the Chemung 

 group 1,000 feet higher at Haskinsville, Steuben county. 



