64 The Ohio Journal of Science [Vol. XXI, No. 2, 



15. Troostocrinus sanctipaulensfs Sp. nov. 

 (Plate I, Fig. 16.) 



Closely similar to Troostocrinus reinwardti (Troost), from the Beech 

 River division of the Brownsport limestone of Western Tennessee. Most 

 of the differences are slight. The sinus in the upper part of the radials 

 tends to be more narrow; the median part of the lower half of the 

 radials, beneath the sinus, tends to be more angular, the intermediate 

 part, along the sutures, being more or less concave; and the lower end 

 of the radial sinus is slightly lower, being in direct contact with the 

 most extended part of the median fold immediately beneath. Cross- 

 sections of the theca agree in being pentagonal along the lower half of 

 the radials and triangular along the basals, the angles occupying the 

 median parts of each of the three basals. In the specimen figured, the 

 basal part of the theca appears less attenuate but another specimen from 

 the same locality shows greater attenuation. The most conspicuous 

 dift'erences are to be noted in the ambulacra. While the number of 

 side-plates in the same length appears to be about the same, namely 16 

 in a length of 5 mm., the individual side plates appear to be more 

 convex, the median line separating the side-plates is much more con- 

 spicuously grooved, and this groove zig-zags less from side to side. 



Locality and Horizon. — From the top of the Laurel lime- 

 stone at St. Paul, Indiana. Four specimens numbered 22909, 

 preserved in Walker Museum, at Chicago University; only one 

 is figured; another presents the details of the oral end of the 

 theca. 



Remarks. — Whether the differences noted above are suffi- 

 cient to warrant the erection of a new species is an open question. 

 Additional specimens are necessary to determine how constant 

 the differences noted are. Students of the crinoidea are aware of 

 the frequency with which species occurring at St. Paul find their 

 nearest relatives in the Waldron, Brownsport, and Racine, 

 many of them showing Gotlandian affinities. From this point 

 of view, the occurrence of the blastoid Troostocrinus, hitherto 

 known only from higher strata, in the upper part of the Laurel 

 formation at St. Paul is entirely normal. 



IG. Troostocrinus reinwardti-minimus Var. nov. 



(Plate I, Fig. 14.) 



Closely related to Troostocrinus reinwardti, from the middle or 

 Troostocrinus zone of the Beech river division of the Brownsport forma- 

 tion in western Tennessee. It differs in being much smaller, and more 

 slender; compared with the total length of the radials, the triangular 

 parts between the radial sinuses are relatively shorter; moreover, the 



