330 NORTH AMERICAN INDEX FOSSILS. 



i88a. C. boothi var. calliteles Green. (Fig. 1647, c.) Devonic. 



Genal spines reaching the eighth segment. Neck ring very broad, 

 bearing a stout, spine-Hke node at its center. Each annulation of 

 the thoracic axis bears a similar node. Pygidium with the lateral 

 lobes smooth, narrow, lanceolate, elevated along the middle, and 

 tending toward a parallel arrangement, with the outer ones much 

 longer than the inner ones; the middle or axial lobe is, in adults, 

 shorter than the rest but longer than in C boothi and acutelv 

 angled ; in young specimens it is very small. 



Hamilton and Tully of New York. 



Subclass Phyllopoda Latreille. 



Small Crustacea of elongated form, often with distinctly seg- 

 mented bodies; body covered usually with a flat, shield-shaped or 

 laterally compressed carapace, producing in the latter case a bivalve 

 shell ; modern species live in fresh water or in salt marshes. 



Literature. 

 1882. Clarke, J. M. Am. Journ. Science, 23 (Devonic). 

 1888. Hall, James, and Clarke, J. M. Pal. N. Y., 7, p. 206. 

 1862. Jones, T. Rupert. A Monogragh of the Fossil Estheriae. 



Palaeontographical Society Monographs, Vol. 14. 

 1900. Clarke, J. M. Occurrence of Phyllopod Crustacean Estheria, 



etc., in Eastern N. Y. State Pal. Report, 1900, p. 103 (Mus. Bull. 



54, Vol. I). 



Order BRANCHIOPODA Latreille. 

 L Estheria Riippel. 



Carapace bivalved ; the two valves are thin, rounded, and united 

 by a straight, toothless margin. External surface with concentric 

 ridges or striae, between which are more or less regularly interlac- 

 ing or branching striae; beaks not sharply defined, the umbonal 

 region sometimes bearing a strong eye or muscle node. Devonic- 

 Recent. 



I. E. membranacea Pacht. (Fig. 1648.) Devonic. 



Subcircular ; beak subcentral ; concentric lines rather prominent, 

 numerous; hinge line straight in front of and behind the beak. 



Oneonta-Catskill of New York; Old Red Sandstone of Europe. 



