572 NEW YORK STATE MUSEUM 



m i n u t u 1 a was attached to stems of Diplograptus; the 

 writer has noticed several cases of apparent attachment of valves 

 of P a t e r u 1 a to rhabdosomes of graptolites in the shales of 

 Mt Moreno. Farther, the accumulation of these shells in small 

 heaps must be considered as indicative of a preceding drifting of 

 this slowly settling organic detritus. 



§ 2 PELEOYPODA 



Technophorus cancellatus sp. n. (see pi. 1, fig. 

 19-25) 



Shell small, moderately convex, elongate, length twice the 

 hight, greatest length in about the middle, subalate posteriorly; 

 cardinal margin short and straight, anteriorly longer, slightly 

 concave posteriorly; anterior end rounded, ventral margin first 

 convex, then gently concave, the postero-basal part produced, 

 the posterior margin slightly concave^ vertical; postero-cardinal 

 angle slightly truncate; beak sub-anterior, of moderate size and 

 convexity, little elevated above the hinge line. 



Surface uniformly convex in the middle and anterior parts, 

 with a broad, shallow depression extending from the beak to the 

 postero-ventral margin; post-cardinal slope with two straight, 

 diverging, strongly projecting angular ridges or folds, which ex- 

 tend to the postero-ventral angle, and are separated by a rounded, 

 ventrally deepening sulcus; posterior wing traversed by another 

 oblique and shallower depression and posterior extremity slightly 

 raised. Surface marked by equal filiform, concentric lines, which 

 on the anterior and middle parts pass parallel to the ventral 

 margin, between the post-cardinal ridges turn upward, and on 

 the posterior wing swing obliquely forward; these are crossed 

 on the anterior and middle parts by another system of vertical, 

 more closely arranged thread-like lines, which in smaller speci- 

 mens appear only between the concentric lines, in larger speci- 

 mens become continuous and more prominent than the latter. 



Casts with a deep, backward curving impression in front of the 

 beak a^nd a corresponding shallower, forward curving impression 



