DESCRIPTIONS 01 THE SPECIES. - 13 



from the sutures separating the side plates themselves, and must have been in direct 



communication with the pores (PI. VIII. tig. 21). In Granatocrinus the hydrospires 

 are few in number. G. Norwoodi possesses two on each side of an ambulacrum, 

 whilst G. campanulatus, G. orbicularis, G. ellipticus, ami G. Derbiensis have onlj one 

 each (PI. XVII. tigs. 3-8). The lancet-plate rests between these two hydrospire-tube . 

 whose inner walls appear as the hydrospire-plates between it and the sides of the sinus 

 (PI. X. figs. 12-14). It sometimes helps to support the side plates, as in G. Norwoodi 

 (PI. X. fig. 11; PL XI. fig. 14). 



Our researches amongst the British species of Granatocrinus have not rewarded us 

 by the discovery of any summit-plates closing the central aperture, like those which 

 commonly occur in the American G. Norwoodi (PI. VII. figs. 4, 11, 13). The calyx 

 in this genus is highly ornate. Concentric strice, often becoming reticulate, or line 

 granules, arranged in lines, cover the plates (PI. VI. fig. 21 ; PI. VIII. tigs. 13, 14, 10, 

 10 ; PI. IX. figs. 1-4, 8-15 ; PI. X. figs. 5-10, 16). 



Species. The species which we are now able to refer with any certainty to Grana- 

 tocrinus, in its most restricted sense, are the following : — 



Pentrcmites campanulatus, McCoy. Carboniferous Limestone; Derbyshire. 



Pentremites Derbiensis, G. B. Sby. Carboniferous Limestone; Derbyshire and 

 Lancashire. 



Pentremites elliptica, G. B. Sby. Carboniferous Limestone ; Derbyshire, Lan- 

 cashire, and Yorkshire. 



Granatocrinus McCoyi, E. & C (MS.). Carboniferous Limestone ; Lancashire. 



Pentremites Nonooodi, O. & S. Upper Burlington Limestone, Subcarbonifemu^ ; 

 Iowa, Illinois, Missouri. 



Granatocrin us Xorwoodi, var. fimbriatm, M. & W. var. Upper Burlington Lime- 

 stone, Subcarboniferous ; Iowa. 



Pentatrematites orbicularis, G. B. Sby. Carboniferous Limestone ; Lancashire. 



In addition to the British species here mentioned, two others have been described, 

 viz. Mitra Iiumerostellata, Cumberland 1 , and If. Hibernica, Cumb. 2 , which appear to 

 us to fall within the genus Granatocrinus. We have, however, quite failed to identify 

 them with any of the later-described species, and they are known to us only through 

 Cumberland's descriptions and figures. Neither are we acquainted with the form for 

 which the Messrs. Austin proposed the MS. name of Orbitremites (jlobosus 3 . 



Of the sixteen species of Granatocrinus which have been described in America, 

 G. Nonooodi is the only one which we can with any certainty refer to this genus. 



1 Reliquiae Conservatoe, 1826, p. 35, t. A. figs. 1-3. 



2 Loc. cit. p. 34, t. B. figs. 1-4 (bottom group). 



3 Ann. & Mag. Nat. Hist. 1842, vol. s. p. 111. 



2 i 2 



