370 



bulletin: museum of comparative zoology. 



limestone. This specimen may be described as follows. The body 

 is rather badly crushed, and lacks the entire apical portion, and one 

 ambulacral area. When perfect the specimen must have been nearly 

 one inch high, conical, with a flat base. The ambulacral areas are 

 long, narrow, and convex, expanding only slightly towards the apex. 

 The lancet-plate is prominent, narrow, occupying about one half the 



1 



Fig. 1, 2. Pentremites conoideus Hall. A crushed specimen from the Madison 



limestone at Old Baldy, Mont. 1. 

 crum. X 10. 



The specimen. X 



2. Detail of ambula- 



ambulacral area. Side-plates narrow, with minute pits for the inser- 

 tion of the brachioles. The base is badly fractured, and the sutures 

 of the basal plates are obscured. The fork-plates are large, deeply 

 depressed along the sutures, and ornamented by fine striae which are 

 to some extent parallel to the median suture of the interambulacral 

 area. There are thirteen side-plates in five millimeters. The speci- 

 men is in the Carnegie Museum, Pittsburgh, Penn; 



Pentremites godoni Defrance. 



Pentremites godoni? Defrance. Meek^ Rept. U. S. geol. survey, Montana, 

 Idaho, Wyoming, and Utah, 1873, p. 469, 470. 



This species, or a closely related form, was noted by Meek in Car- 

 boniferous rocks at two localities in Montana, Old Baldy near Vir- 

 ginia City, and the Divide between Ross Fork and Lincoln Valley. 



Pentremites subconoideus Meek. 



Pentremites s^ibconoideus Meek, Rept. U. S. geol. survey, Montana, Idaho, 

 Wyoming, and Utah, 1873, p. 471. Hambach, Trans. Acad. sci. St. Louis, 

 1903, 13, p. 38. 



