DESCRIPTIONS OF Till-: SPECIES. 281 



Remarks. This type is represented by a single species, one of the two for which 

 the genus Pmtremitidea was originally established by d'Orhigny upon a character 

 which eventually proved to be non-existent. But when we redefined Pmtremitidea 

 in 1882, taking as the type P. J'ailleffei, d'Arch. & do Vern., sp., we followed 

 d'Orbigny's classification and still regarded Pentremites Schulzi as belonging to that 

 genus, though we pointed out that it represented an extreme form of modification in 

 almost every one of the generic characters. The subsequent examination of some 

 better preserved material than was at first available has shown us, however, that the 

 hydrospires of Pentremites Schulzi are formed in a totally different manner from 

 those of Pentremites and Pmtremitidea (PI. I. figs. 6, 7; PI. V. figs. 3, 5); for the 

 slits are not concentrated at the bottom of the radial sinus as in those types, but are 

 well separated from one another on the sloping sides of the radial sinus, just like 

 those of Codaster and Phamoschisma. The slits thus pierce the radial and deltoid 

 plates directly, as is well shown in PI. V. fig. 24 and PI. XVIII. fig. 2. The latter 

 figure may be advantageously compared with fig. 1 on the same Plate (Codaster) and 

 also with figs. 3-6 (Pentremites). The distal termination of the hydrospires against 

 the bodies of the spade-like radials of Cryptoschisma is well seen in PI. XVI. 

 figs. 3, 4. The slits, however, are entirely concealed by the broad ambulacra, no 

 part of them opening directly to the exterior, as is the case in the Phsenoschismida; ; 

 and it is this character which is specially distinctive of the genus. Another pecu- 

 liarity is the very considerable truncation of the summit, which is more evident than 

 in any Blastoid except Codaster trilobatus (PI. XIII. figs. 1, 3, 15). The base is 

 much elongated and often marked by a circular constriction, as shown in PL V. 

 figs. 25, 26. The former figure shows that the upper part of the calyx may be 

 sometimes bent to one side, as in the Mesozoic Holopidae and Eugeniacrinidse. As 

 far as our experience goes, however, this is by no means a common character. 



Species, Distribution, and Type. Cryptoschisma is represented by but one species 

 only, the Pentremites Schultzii of dArchiac and de Verneuil, which occurs at two 

 horizons in the Lower Devonian of Spain. 



Cryptoschisma Schulzi, cTArchiac & de Verneuil, sp. 

 (PL V. figs. 23-26 ; PL XIII. fig. 20 ; PL XVI. figs. 3, 4 ; PL XVIII. fig. 2.) 



Pentremites Schultzii, d'Arch. & de Vern., Bull. Soc. Geol. France, 1845, torn. ii. p. 479, 



t. 15. f. 12 a & ft, f. 13 a & b. 

 Pentremitidea Schultii, d'Orbigny, Prod. Pal. Strat. 1849, torn. i. p. 102. 

 Pentremitidaa Schultii, d'Orbigny, Cours element. Pal. et Geol. 1852, ton,, ii. fasc. 1. p. 139, 



f. 287. 

 Pentatrematites Schultzii, Roemer, Archiv f. Naturgesch. Jahrg. xvii. Bd. i. p. 369, t. 7. 



f. 18 a & b. 

 Pentremites Schultzii, Dujardin & Hupe", Hist. Nat. Zooph. Echinod. 1862, p. 98. 



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