97*2 PALAEONTOLOGY OF NEW-YORK. 



The following species of Entomostraca have been recognized in this group* : 



Leperditia joiiesi ( n. s.). 



Plate LXXIX A. Fig. 5 « - «. 

 Leperdita (Ci/therina) altaf Palajontology of New-York, Vol. ii, pa. 331, pi. 78, f. 2. 



Carapace large : valves strongly convex, gibbous in the middle ; an- 

 terior end narrower, rounded ; posterior end broadly and regularly 

 rounded ; ventral margin broadly arching and abruptly incurved. The 

 dorsal angles are expanded, and a distinct narrow border extends 

 thence along the anterior and posterior ends, to where the ventral 

 margin begins to curve inwards. The anterior tubercle is distinctly 

 prominent, and above a line extended from the central tubercle to the 

 anterior dorsal angle. Central tubercle moderately prominent, and 

 distinguishable by the reflection of light upon the surface, the greatest 

 convexity of the valve being posterior to the middle. Surface papillose. 

 In casts, the place of the central tubercle is seen, with the radiating 

 vessels distinctly visible in meandering granulose lines extending to- 

 wards the posterior and ventral margins. 



This species resembles in form the L. alta, and I had not originally separated it 

 from that species. It differs, however, in its usually larger size and somewhat greater 

 proportional breadth, while the papillose surface of the last is always a reliable 

 feature for distinguishing it from that species. In specimens of the same size, it is 

 more convex in the middle than L. alta. 



Fig. b a, b. A young and medium-sized specimen, natural size. 



Fig. 5 c. A full-grown specimen, natural size. 



Fig. 5 d. Profile view of the same. 



Fig. 5 «. An enlargement of the surface, showing the papillose markings. 



Geological position and locality. In the coralline limestone, Schoharie, and in the 

 same position in Herkimer county. 



• The Ltptrditia jontti U introduced in this place, to correct the erroneouB reference of the species in 

 Vol. II. 



