JO The American Geologist. February, \%m 
are eight small spiracles at the summit and a large anal 
opening. Whole surface of the plates finely granular. The 
foot-like projections at the bottom of the ambulacra point 
outward. 
This species is not unlike Meek & Worthen's Pentremites 
cornutus but is very much smaller and from a dififerent hori- 
zon. Moreover the interradials are extended more nearly 
straight up and are more slender and more acutely pointed. 
Our species occurs in the cjuarry at Grand Tower, 111., and 
Wittenberg, Mo., in the Warsaw? (St. Louis) limestone, asso- 
ciated with Pentremites conoidens and Pentremites bennedicti. 
The specimen figured is one of the largest found as many are 
little larger than a large radish seed. 
This is probably the smallest known American blastoid. 
Troostocrinus? dubius, (nov. sp.) 
Fig. 36. Side view of a large specimen, natural size. 
Fig. 37. Ventral view of a smaller individual, twice natural size. 
Fig. 38. Basal view, three diameters. 
Basal cup triangular or pyramidal. Hight and width about 
equal. The radial sutures apparently extend to the summit 
as no interradials are visible externally. The top of the anal- 
interradial area is horn-like or extends somewhat above the 
tops of the other areas in some of the specimens. Except the 
anal opening" and the central uncovered area, no other open- 
ings are visible. The ambulacra are over a third of the length 
of the entire body and lie a little below the edges of the 
radial lips. The number of pore pieces on either side of the 
laucet plate in each area is from fifteen to twenty. 
No columnar cicatrix was noticed on any of the specimens, 
and if present the stem must have been very slender. The 
ornamentation of the plates is fine parallel striae. 
This most interesting little blastoid comes from the Delthy- 
ris Shaly limestone of the Lower Helderberg group, two miles 
below Wittenberg, Mo., and was found associated with Dal- 
manites tridentifera, Cyrtina dalmani and Platyceras pyrami- 
datum. 
This species will, doubtless, be found to possess good char- 
acters for a new genus, as it has little to ally it to Troosto- 
crinus. 
