KONINCK NEW PALEOZOIC CRINOTDS. 



183 



it is probable that the disposition of the other plates of the calix is the 

 same in that genus as in that which I here propose. 



Position and Distribution. — I know, as yet, but two species of the 

 genus Pisocrinus, both from the Upper Silurian limestone of the 

 neighbourhood of Dudley, where they have been discovered by Mr. 

 John Gray, of Hagley, whose patient researches have enriched the 

 English Silurian fauna with a great number of remarkable animals. 



1. Pisocrinus Pilula. Be Koninck. PL TY., fig. 8 — 11. 



The Calix of this species is of the size of a large pea, of which it puts on at the 

 same time the form, saving the truncation, produced by the opening above. The 

 surface is entirely smooth, and also slightly glistening. The ha&e is perfectly of 

 the form of an equilateral and slightly broad triangle. The articulation of the 

 stem is placed at the bottom of a rather deep and wide hollow. The suh-radial 

 plate, somewhat broader than long, is bounded in its upper part by an obtuse 

 angle, which arrests it at a short distance from the upper edge of the calix. It 

 results from this that the two radial plates, resting upon this plate, are not quite 

 triangular in form (Fig. 8). 



The five radial plates have their upper surface deeply farrowed for the reception 

 of the second plate, which should surmount them, but which remains unknown 

 to me. The opening of the calix is almost circular, or rather sub-decagonal through 

 the little slopes existing on the various pieces ; that which corresponds to the 

 anal side is a little more decided, as is displayed in figure 11. 



Affinities and Differences. — This species distinguishes itself from the 

 following by the absence of all ornament on its surface, and by its 

 much more globular form. 



Dimensions. — Length about 5™°^ ; diameter of same dimension ; 

 diameter of the articulation of the stem V^^. 



Position and Locality . — I know as yet but two specimens of this species; 

 one in the rich collection of Mr. Gray, the other in my own. I owe 

 the last to the kindness of Mr. Lewis of London, whom I have seen 

 with regret abandon the study of palaeontology, to the advancement of 

 which he has contributed powerfully by his active researches. 



Explanation of figures. — PI. lY: — 



Fig. 8. — Specimen, magnified, view of the anal side. In the collection of Mr. 

 Gray, of Hagley. 



Fig. 8 a. — The same, of natural size, view of the same side. 



Akad. der Wiss., 1856, No. 6, p. 248), for some palaeozoic crinoids from the Eifel, 

 is identical with the genus Triacrinus. This is only possible for me to decide by 

 an inspection of the specimens described by von Miinster, of which the figure in 

 outline (Beitrage z. Petrefakt., I, pi. I, fig. 4, c) is evidently defective ; for, if it 

 were actually the expression of the reality, it would follow that there existed 

 crinoids with three rays instead of five, which is not probable. 



