DE8CBIPTI0NS OS THE SPECIES. 181 



basiradial sutures; summit depressed; base sharp; section strongly pentagonal; 

 periphery nearer the summit than the base. Basal plate-, forming a small, slightly 

 expanded cup. Radial plates arched, broad at their bases, expanding very Blightly 

 upwards to the level of the lips; the limbs then rapidly decrease towards the summit, 

 and form strong projecting lobes around it ; sinuses straight and very narrow ; radial 

 angle about 134 . Deltoid plates almost invisible. Ambulacra narrow. 



Remarks. Although we can only give a limited definition of this species, it is never- 

 theless sufficient to show how clearly distinct the type is from any other I't tilnmitidea. 

 On the other hand, the resemblance of the calyx in general form to that of an Oro- 

 phocrinus, especially in the typical species 0. stelliformis, O. & S., sp. (PI. XVI. 

 figs. 5. 7). and in 0. verus (PL XV. fig. 3), is very remarkable; but here, of course, 

 the resemblance ceases. The radial angle, the leugth of the ambulacra, and the 

 greater amount of calycular surface between their distal extremities and the base of 

 the calyx in P. similis, separate it from P. clavata, Schultze, sp. (PI. IV. fig. 18), to 

 which it is nearly related. The form of the radial plates in P. angulata (PI. IV. 

 fig. 13), irrespective of other characters, at once separates the latter from P. similis. 



The Messrs. Sandberger have described l a peculiar form from the Rhenish Devonian 

 rocks [Pentatrematites planus), which we believe to be an aberrant Pcntrcmitidea, 

 but it is much too depressed a species to be confounded with ours. There is another 

 Eifel species which has received from Dr. J. Steininger the name of Pentremites 

 gracilis' 2 , but the meagre description given renders it quite impossible for us to form 

 any idea of what it may be like, a difficulty which has been already noticed by Prof. 

 F. Roemer 3 . It is also a noteworthy fact that Schultze does not record Steininger's 

 species in his well-known Monograph of the Eifel Echinoderms. 



Locality and Horizon. Priim: Eifel Limestone, Middle Devonian (auctorum), but 

 Lower Devonian (Barrois). 



Genus MESOBLASTUS 4 , gen. nov. 

 Granatocrinus (pars), E. & C, Ann. & Mag. Nat. Hist. 1882, vol. ix. p. 236. 

 Gen. Char. Calyx generally resembling that of Granatocrinus in the form and 

 proportions of its component parts. The base is concave or protuberant. The radial 

 plates are long, and the deltoid plates small, short, and unequally rhombic ". Spiracles 

 distinctly double as a rule, but sometimes incompletely divided. Their distal border 

 is formed by side plates which rest in the angle between bydrospire-plate and lancet- 

 plate, and almost or entirely conceal the latter. Hydrospire-folds few in number 

 (more than three?). Posterior spiracles confluent with anus. 



1 Verstein. Ithein. Scbichrcn Nassau. 1850-56, p. 403, Atlas, t. L'.J. fig. -la & b. 



■ Jahrcsb. Schnl-Cursiis, L848-49, Gjmn. zu Trior. L849, p. 19. 



3 Arehiv f. Xaturgeseh. 1851, Jabxg. xvii. Bd. i. p. 374. 



* fiiaoi, intermediate. 



5 »'. e. so far as the species are knowu to us. 



