MIOCIDARIS. 247 



spinules directed distally. Bather gives much detail in regard to the structure of this species, 

 and saj^s there is no good ground for separating verneuiliana and keyserlingi specifically. 



Lower Zechstein, Permian, Corbusen, Ronneburg, Germany, cotypes, Dresden Museum; 

 near Posneck, Thuringia, Museum of Comparative Zoology 3,193; Permian, Zechstein, 

 Freiburg i. B. Museum; Permian, Humbleton Hill and Tunstall Hill, British Museum. 



* Miocidaris cannoni sp. nov. 



Text-figs. 239a— 239e 



This species is represented by a single specimen kindly sent to me by Mr. George L. Cannon, 

 instructor in geology and biology in the Denver High School, of Denver, Colorado. It was 

 received too late (August, 1911) to be figured otherwise than by insert cuts, which with the 

 description are inserted in proof-sheets. 





Text-figs. 239a-239e. — Miocidaris cannoni sp. nov. MilLsap Formation, Lower Carboniferous, near Denver, 

 Colorado. Holotj-pe. Museum of Comparative Zoology Collection 3,201. 



a. View of the specimen. X 2. A few interambulacral plates are in place in interambulacra A, C, and E. The 

 rest of the specimen consists of an internal siliceous mold. 



b. Outline of an internal impression of an interambulacral plate from area C. X 4. Showing elevated mamelon. 



c. View across the dorsal part of interambulacrum C. X 4. Showing fragments of three plates in place which meet 

 the median suture; the outlines of the plates are restored, as indicated by dotted lines. 



d. Interambulacral plate from near the mid-zone in area E, with about four opposing ambulacral plates, which are 

 indicated by siliceous casts of the pore-pairs. X 4. 



e. Section of an interambulacral plate in the dorsal part of area E, showing its beveled edge on the adradial suture. 

 X 4. The outline of tlie ambulacrum is seen in section and siliceous molds of the pore-pairs exist as elevated plugs. 



The specimen is a siliceous internal mold and about half of it is embedded in a hard sili- 

 ceous chert. A few fragmentary worn interambulacral plates are preserved. The specimen 

 shows two ambulacral areas, one interambulacrum complete from the ventral border to the 

 apex, and parts of two next adjacent interambulacra. The impressions of sutures on the mold 

 are clear only in parts, but they are perfectly clear in the plates, as far as these are preserved. 



The test is depressed spheroidal, free from all distortion, and measures about 20 mm. in 



