106 PALEOZOIC ECHINODERMATA. 



articular surface flat with an articular ridge running its whole 

 width ; all the plates slightly convex and smooth. Width of 

 cup 9 lines. 



Rare in the carboniferous limestone of Derbyshire. 

 {Col. University of Cambridge.) 



Cupressocrinus impressus (M'Coy). 



Sp. Char. Cup four times wider than deep ; pelvis concealed in 

 a deep circular pit, out of which spring the broad ends of five 

 ovato-lanceolate first-costals, the apex of one of which is trun- 

 cated to support a small elongate interscapular plate, and on 

 its side rests a somewhat larger intercostal plate ; scapulce 

 about one-third wider than long, pentagonal, the two lower 

 sides concave, and the lower angles very much prolonged to 

 fit between the lanceolate costals ; substance of the joints very 

 thick, projecting far into the visceral cavity, a strong perfo- 

 rated articular ridge runs across the top of the scapulae ; all 

 the plates shghtly convex and smooth. 



Distinguished from the C. calyx by its deeply impressed pelvis 

 and long, lanceolate first-costals. 



Not very uncommon in the carboniferous limestone of Derby- 

 shire. 



{Col. University of Cambridge.) 



( Semiarticula ta . ) 

 Poteriocrinus nuciformis (M'Coy). 



Sp. Char. Body subovate, pointed below, constricted above from 

 the upper margins of the scapulse being narrower than their 

 lower portion ; pelvic plates very small, form unknown ; first- 

 costals long, pentagonal, very narrow below, giving a pointed 

 appearance to the lower portion of cup ; second costals large, 

 tumid, subhexagonal, nearly twice the length of the first- 

 costals, a little less wide than long ; scapulce pentagonal^ about 

 one-third wider below than above, giving a very perceptible, 

 constricted appearance to the upper part of the cup, articula- 

 tions apparently the whole width of the plate ; irregular in- 

 tercostal large, subhexagonal, supporting two small pentagonal 

 interscapulars ; surface smooth. Length of cup 8 lines, greatest 

 diameter (at second costals) 7 lines. 



This closely resembles the P. Bockschii figured by Geinitz in 

 his ^Grundriss der Versteinerungskunde,^ t. 23. f. ]3, but of 

 which no description or definition has been published. 



Not uncommon in the carboniferous limestone of Derbyshire. 

 {Col. University of Cambridge — two examples.) 



