CRUSTACEA. 
7 
Binnewater, Ulster county.” This reference is probably correct, as the matrix 
of the larger trilobite shows a well-defined specimen of Spirifera arenosa, an 
Oriskany species, and Mr. Whitfield has mentioned the occurrence of a young 
individual of Strophodonta magnijica upon the smaller specimen. 
Homalonotus Dekayi. 
PLATE II, FIGS. 1-11; PLATE III, FIGS. 1-5; PLATE ,IV, FIGS. 1-6; AND PLATE V, FIGS. 1-10. 
Diplewra Dekayi, Green. Monog.,Trilob. North America, p. 79. 1832. 
Nuttamia sparsa, Eaton. Geological Text Book, p. 34. 1832. 
Dipleum Dekayi, Vanuxbm. Geology of New York. Survey Third Geol. Dist., 150, fig. 1. 1842. 
Dipleura Dekayi, HklIj. Geology of New York. Survey Fourth Geol. Dist., p. 205, fig. 1. 1843. 
Homalonotus Dekayi, Emmons. Manual of Geology, pp. 14G, 147, figs. 134, 135. 1800. 
Homalonotus Dekayi, Hall. Fifteenth Rept. N. Y. State Cab. Nat. Hist., p. 113. 1862. 
Homalonotiis Dekayi, Hall. Illustrations of Devonian Fossils, plates ii, iii, iv, v. 1876. 
General Form and Proportions. Elongate, linguiform, anterior and posterior 
extremities produced and sub-angulate; lateral margins nearly straight and 
approximating posteriorly. N^Length to width about as 2 to 1. 
Surface depressed-convex or flattened, obscurely trilobate, abruptly de¬ 
flected along the lateral margins. 
Cephalon broadly sub-triangular in outline, posterior side the longest; angles 
rounded. In the usual condition of preservation the lateral margins approach 
each other at an angle of ninety degrees, making, at the basal margin, an 
angle of forty-five degrees. With the retention of normal convexity, the 
shield is nearly equilateral. Length to width as 1 to 1.9. The surface is 
normally depressed-convex or flattened, deflected beneath the ocular nodes; 
trilobate; frontal and lateral areas narrow, the former produced into a 
short prora. 
The facial sutures take their origin on the lateral margins of the doublure in 
front of the genal angles and pass inward, parallel to the posterior margin 
of the cephalon, to the eye, thence forward with a broad curve inward to 
the anterior margin at the base of the prora, bending thence on to the epis- 
tomal doublure, meeting at its inferior margin. The branches of the facial 
suture are united on the upper surface of the prora by a straight transverse 
