208 CATALOGUE OF THE BLASTOIDEA. 



Group in Monroe County, Illinois, and not in the Archimedes beds of Randolph 

 County, as cited by Roemer." We have some doubt whether the species which they 

 figure under this name is identical with Roemer's type. 



Locality and Horizon. Washington County, Indiana: St. Louis Limestone, Sub- 

 carboniferous. 



TRIC03LOCKINUS MEEKIANUS, sp. 110V. 



(PI. XVI. figs. 17, 18.) 



S-p. Char. Calyx slender, elongately pyramidal ; summit very small and very much 

 contracted; base with shallow lateral excavations; section pentagonal, with straight 

 or flat sides ; periphery rather nearer the base than the summit. Basal plates form- 

 ing a low triangular cup, with the three carina? truncated, and not projecting below 

 the central triangular surface which bears the facet for the columnar attachment. 

 Radial plates with slightly converging lateral margins ; bodies much shorter than the 

 limbs, and moderately carinate, the lateral basal excavations extending but little on 

 to their surfaces ; limbs narrow with flat sides, not sloping at a high angle ; sinuses 

 three quarters the length of the calyx with high sides ; interradial sutures not in 

 concavities. Ambulacra rather deeply sunken. Ilydrospires unknown ; spiracles 

 apparently mere slits only. Ornament not preserved. 



Remarks. Although our specimen is entire, it is in a very bad state of preservation, 

 and does not afford all the data which we could desire. We should unhesitatingly have 

 referred this form to Worthen and Meek's Triccelocriims obliquatus ' had it not been 

 for two points of difference between it and their figures. The interradial sutures in 

 the latter are placed in concavities, at least so Ave infer from the shading of the two 

 illustrative figures ; but in our specimen, the sutures in question are on flat surfaces 

 and there are no interradial re-entering angles ; while the ambulacra are relatively 

 half as long again as in Worthen and Meek's species, and the base much less strongly 

 hollowed (PI. XVI. figs 17, 18). We do not think therefore that our species can 

 be referred to Worthen and Meek's type ; but, on the other hand, we greatly doubt 

 whether the latter is identical with that previously described by Roemer under the 

 same name. 



We are a little in doubt about the deltoids of T. Meekianus, for there are some lines 

 on the exterior of the calyx which might be thought to indicate that the deltoids 

 appear externally (PI. XVI. fig. 18). These are shown rather too plainly in our 

 figure, and we suspect that they are really only cracks in the calcite, just as in the 

 case of Troostocrinus Reinwardti and Shumard's specimen of Metablastus lineatus. 



Triccelocrinus Meekianus comes rather near to Metablastus Wachsmuthi. In fact 

 these two species form the best connecting links between the two genera that we 

 know of. The much longer ambulacra of the first-named, however, and the lateral 



1 Report Geol. Survey Illinois, 1875, vol. vi. p. 521, pi. 31. figs. 4a, 4b. 



