MELOCRINID^. 305 



equal, arranged as in Melocrinus. Four of the radials heptagonal, the 

 anterior one hexagonaL Costals two ; the first hexagonal, the second gen- 

 erally pentagonal. Distichals 1X10, all axillary. The first palmar, and 

 sometimes the second, takes part in the calyx ; the succeeding ones being 

 arm plates. Arms long, simple, straight, biserial ; fringed by good-sized 

 pinnules, which are in contact. Interbrachials three or four, but no inter- 

 distichals. Structure of ventral disk and anus unknown. Column round ; 

 tapering. 



Distiihution. — The genus is known only from the Oriskany Sandstone of 

 Maryland. 



Type of the genus : Techiocrinus spinulosus Hall. 



Bemarhs.— Technocrinus differs from Mariacrinus and Melocrinus in the 

 perfect pentamerous symmetry of its dorsal cup, and from the former in hav- 

 ing one instead of three to four distichals, no interdistichals, and the arms 

 arranged in an almost continuous series around the calyx ; while the arms of 

 Mariacrinus are arranged in groups. It differs from Melocrinus in having sim- 

 ple arms given off directly from the calyx, and not from its tubular extensions. 



Techiocrinus striatus and T. sculptiis Hall, were described from detached 

 basal plates. 



Technocrinus spinulosus Hall. 

 Plate XXII. Fig. S, 



1859. Hall ; Palseont. New York, Vol. III., p. 140, Plate 85, Pigs. 1-18. 

 1881. W. and Sp. ; Revisiou Palseocr., Part II., p. 117. 



Calyx subglobose, the arm bases slightly contracting. Plates of the 

 dorsal cup marked by a central spine or node, surrounded by smaller 

 nodes, which vary in number among the plates. From the nodes tw^o to 

 four parallel ridges pass out to the sides, and these are continued upon 

 adjoining plates. Near the arm bases the ridges gradually disappear, and 

 the plates are marked only by a central spine. 



Basals four, of medium size, forming a shallow basin with five sets of 

 four ridges, each set communicating wuth those upon the radials. Eadials 

 and costals nearly as wide as long, decreasing in size upwards -, the second 

 costal but half the size of the first. Distichals one to each side of the cos- 

 tal axillaries. The first palmar enclosed in the calyx. Arms twenty, stout, 

 rounded ; composed at their bases of cuneate pieces, which interlock farther 

 up, and gradually become biserial. Interbrachials apparently four. All 



39 



