CRUSTACEA. 151 



Cheeks broad, depressed about the base of the eyes and sloping with slight 

 concavity to the margins. Occipital furrow narrow and deep; occipital ring 

 rounded. 



Eyes small, and elevated above any other portion of the head. 



Surface smooth or minutely punctate. 



The other parts of the animal have not been discovered. 



Dimensions of the cephalon. The single specimen which has been observed 

 measures 2 mm. in length and 3.8 mm. in width. 



Observations. This species, in its general features, in the convexity of the fron- 

 tal area and the smoothness of the test, appears to be closely similar to Cyphaspis 

 minuscula. It differs from the latter in its more elevated and wider bonier and 

 shorter cheek-spines, as well as in its smaller size, it being one of the most minute 

 species of Cyphaspis yet observed in the Devonian rocks. Its occurrence in the 

 beds of the Chemung group makes it the latest known representative of the 

 genus, and with the exception of the somewhat doubtful species, Phacops nupera, 

 is the only trilobite known from this formation. 



Distribution. Chemung group. Chemung county. 



Cyphaspis ccelebs, n. sp. 



PLATE XXIV, FIG. 1. 



General Form and Proportions. Outline elliptical, lateral margins rapidly 

 curving to the pygidium. 



Surface depressed, distinctly trilobate. Axis broad, rapidly tapering 

 posteriorly. 



Cephalon semi-elliptical in outline; marginal rim flattened, slightly reflexed; 

 produced at the genal angles into spines, which extend to the pygidium. 

 Frontal area convex, abruptly deflected from the glabella; lateral area 



depressed-convex. 



Glabella ovoid ; basal lobes distinct. Palpebral lobes high, distant; palpe- 

 bral sulcus broad and deep. 



