﻿208 SMITHSONIAN MISCELLANEOUS COLLECTIONS [VOL. 47 



not a rare species, yet owing to the pseudomorphous, thin-shelled, 

 hollow condition of the fossils, bnt few specimens hold together for 

 the collector. All the specimens examined were found in the vicinity 

 of Cumberland, Maryland. 



Cat. number 33,661, U. S. N. M. 



Class CYSTOWEA Jaekel 1 



" Definition. — Cystoidea are Pelmatozoa whose cup or ' theca ' is 

 closed to the mouth, penetrated by pores (thecal pores), and whose 

 ambulacral radial vessels have egress only through the mouth. The 

 skeleton of the theca consists of non-movable polygonal plates, very 

 rarely without a stem and by which it is anchored or free. The 

 ambulacral radial-vessels are either restricted to the region about the 

 mouth or they bifurcate and spread over the theca, but are always 

 elevated distally in skeletal arm-appendages ('fingers'). The 

 fingers [brachioles is the term used in this paper] are biserial, un- 

 divided, and have groove-plates [= ambu.lacralia of this paper] , but 

 are without pinnules. The mid-gut is solar, the end-gut often turned 

 to one side, the anus is in the side of the theca, not always in inter- 

 radius I :V, but is always situated outside of the bases of the fingers 

 and generally is closed by a plated pyramid. As sexual organs the 

 axial-sinus of the body-cavity originally functioned, opening out- 

 wardly in a pore (' parietal pore '), suborally in the interradius I :V. 

 The position of the primary stone-canal remains fairly constant and 

 opens outwardly near the mouth and above the parietal pore [in the 

 following pages the writer has used the term hydropore] in the 

 madreporite, but sometimes through regression is united with the 

 parietal canal. The latter, the primary stone-canal, and their pores 

 are situated in the vertical-mesenterium ('parietal septum')." 



Order DICHOPORITA Jaekel 



" Definition. — Dichoporita are Cystoidea whose thecal-pores are in 

 pairs, each pair divided between two plates, situated vertically across 

 the suture lines, slit or tubular-form, arranged parallel and combined 

 into pore-rhombs [== pectinirhombs of this paper] , their ambulacral 

 radial-grooves in special skeletal elements supported by the theca." 

 (Jaekel, p. 178.) 



Suborder Regularia Jaekel 



Dichoporita with the " theca having a base of four plates and four 

 circles each normally made of five pieces. Pores in open adjoining 



1 Stammesges. </. Pel., Berlin, 1, 1899, p. 63. 



