1886.] NATURAL SCIENCES OP PHILADELPHIA. 109 



Radials five, large, irregular in size, four of them arm-bearing, 

 the fifth one not. The articular facet is lateral, horseshoe-shaped, 

 and occupies almost the whole outer face of the radials. Three 

 of the plates have a single facet, but the fourth, which is an 

 axillary, has two, somewhat smaller than those of the others. 

 The non-arm-bearing radial is smaller by more than one-half than 

 any of the rest; it is hexagonal or trapezoidal, and sometimes 

 altogether absent. The anal plate is placed between the lateral 

 faces of two radials, and rests upon the truncate upper face 

 of the larger basal. It is subquadrangular, somewhat excavated 

 for the anal opening, which generally occupies the upper portion 

 of the anal plate, occasionally, however, as in Gaster'ocoma, tire 

 lower side of it. The form of the arms is unknown. 



The interradials appear to be small, but probably are partly 

 hidden from view by the unusually large covering pieces, which 

 occupy the greater part of the ventral surface, and rest against 

 the oral plate, which is extremely large, there being no proximals. 

 The column, like that of Gasterocoma, is provided with a central 

 canal and four peripheral ones. 



The only known species is : 



1856. Nanocrinus paradoxus Muller, Monatsher. d. Berl. Acad., p. 355; also Neue 



Echin. d. Eifl. Kalk.. 1857, p. 249, PI. 2, figs. 18-21. Schultze, 1866, Echin. 

 Eifl. Kalk.. ).. 102, PI. 12, fig. 7. Devonian, Eifel, Germany. 



MYRTILLOCRINUS Sandberger. 



1855. Sandberger, Versteiner. Nassau's, p. 388. 



1857. Pictet, Traite de Paleont., iv, p. 311. 



1862, Dujardin and Hupe, Hist, natur. des Zooph. Ecliinod., p. 108. 

 1862. Hall, 15th Rep. N. York St. Cab. Nat. Hist., p. 142. 

 186G. Schultze, Moii, Echin. Eifi. Kalk., p. 96. 



We have not seen the original description of this genus, but 

 we infer from the notes of Pictet, Schultze and Hall, that Sand- 

 berger described it to possess a quinque-partite, quadri-canalicu- 

 late base. In his figure it seems the central part was represented 

 as undivided, and, curiously enough, the same is the case with 

 Hairs figure of the American species, although he mentions in 

 the description " five basals and five subradials." We cannot 

 understand how a base like this could have been divided into five 

 parts not four aud, therefore, prefer, in default of further evi- 

 dence, to regard it as undivided, although we are well aware that, 

 if any such division did exist, it would prove most satisfac- 



