292 CATALOGUE OF THE BLASTOIDEA. 



(PI. XV. fig. 1) the calyx generally is more elongated, and the ambulacra shortened, 

 thus indicating a departure towards the other British species 0. pentangularis, 

 Miller, sp. (PI. XV. figs. 6, 9). The specimens agree so closely in other respects 

 that it would be impossible to separate them specifically ; and we are the less inclined 

 to do so because our study of the Blastoidea has shown, in the plainest possible 

 manner, that there is a large amount of variability in the characters of a species. 



Localities and Horizon. Whitewell, in Bolland, Lancashire (Presented by the late 

 Mr. John Rofe, F.G.S.) ; Preston, Lancashire : Carboniferous Limestone. 



Orophocrinus pentangularis, Miller, sp. 

 (PI. XV. figs. 5-9 ; PL XVI. figs. 8, 9 ; PL XVII. fig. 14.) 



Platycrinites pentangularis, Miller (pars), Nat. Hist. Criiioidea, 1821, p. 83 [t. 29. figs. 2, 



G, 7]. 

 Mitra depressa, Cumberland, Reliquiae ConservatEe, 1826, p. 33, t. B. f. 3. 

 Pentatrematites pentangularis , G. B. Sby., Zool. Joum. 1855, vol. v. p. 467, t. 33, Suppl. f. 7. 

 Pentremites pentangularis, Phillips, 111. Geol. Yorks. pt. 2, 1836, p. 207. 

 Dimorphicrinus pentangularis, d'Orbigny, Prod, de Pal. Strat. 1849, torn. i. p. 155. 

 Pentatrematites pentangularis, Roeiner, Arcliiv i. Naturgesch. 1851, Janrg. xvii. Bd. i. p. 371. 

 Pentremites pentagonalis, Morris, Cat. Brit. Foss. 2nd edit. 1854, p. 86. 

 Pentremites Water housianus, de Koninck & le Hon, Mem. Acad. Roy. Belgique, 1854, 



torn, xxviii. Mem. 3, p. 203, t. 7. f. 6a-c. 

 Pentremites pentangularis , Dujardin & Hupe, Hist. Nat. Zooph. Ecliinod. 1862, p. 98. 

 Pentremites Waterhousei, Rofe, Geol. Mag. 1865, vol. ii. p. 250. 

 Orophoa-inus pentangularis, et O. Waterhousianus, E. & C, Ann. & Mag. Nat. Hist. 1882, 



vol. ix. p. 252. 

 Orophocrinus (Pentremites) prcelongus, Baily (pars), Proc. Roy. Dub. Soc. 1886, vol. v. 



pt. 1, p. 31, t. i. f. 2, 2 a, 2 6. 



Sp. Char. Calyx a truncated pentagonal pyramid, or elongately parachute-shaped, 

 narrow and funnel-like below, expanding very gradually upwards; summit gently 

 convex, or somewhat depressed in the centre ; periphery at less than a third from the 

 summit, the disproportion in height between the parts above and below this level 

 being very apparent. Basal plates elongate, higher than wide, forming a funnel- 

 shaped cup. Radial plates oblong, large, increasing but little in width, forming 

 quite, if not more than, two thirds the entire length of the calyx ; bodies obtusely 

 rounded and prominent in the middle line, much longer than the limbs ; interradial 

 sutures placed in depressions ; sinuses narrow and short, with simple margins ; lips 

 prominent. Deltoid plates small and rhombic, the anal deltoid rather larger than its 

 fellows, and rounded along its distal margin. Ambulacra short and narrow, raised 

 but little above the margins of the sinuses ; side plates about twenty-five ; lancet- 

 plate partially covered at its proximal end, and entirely so distally, boat-shaped in 

 section ; hydrospire-clefts extending almost the whole length of the ambulacra, but 



