﻿SCHUCHERT] siluric AND DEVONIC CYSTIDEA 211 



plates 7, 8, and 13, consisting of an outer complete circle of minute 

 pieces and the pyramid of 5 pieces. ( >ne basal and 2 discrete-pectini- 

 rhombs 3 with small recesses and few dichopores. 



Ambulacra 4, simple, narrow, and not prominent. These are R I. 

 R II, R [V, R V, equally developed and generally continuing nearly 

 or quite to the column. Brachioles few in number and more or 

 less widely separated. 



Genotype, A. pentrematoides Forbes (1 specimen in II. S. N. M., 

 cat. number 35.137). 



Lepocrinites gebhardii is usually referred to this genus, and al- 

 though the species is closely related, it does not seem advisable to 

 make Lepocrinites synonymous with Apiocystites. The latter un- 

 doubtedly represents an earlier stage in the development of Lepo- 

 crinites, but it is one that should be distinguished; it differs from 

 the later type in having small discrete-pectinirhombs and narrower 

 ambulacra, with the ambulacrals more elongate and narrower, 

 causing the brachioles to become fewer in number (about 20 to 36 

 to an ambulacrum ) and more widely separated. Moreover, the 

 column in Lepocrinites is very peculiar in having 2 distinct parts — an 

 upper consisting of about 15 segments, and a lower in which the 

 segments are fused into a single long, swollen, leech-shaped piece. 

 The latter is characteristic of the genus and is found abundantly in 

 the Coeymans limestone at the base of the Devonic, while other parts 

 of this cystid are very rarely obtained by collectors. For the differ- 

 ences between Apiocystites, Tetracystis, and Jaekelocystis, see the 

 discussion under the last two genera. 



The species referable to Apiocystites are the following: A. pentre- 

 matoides Forbes of the Wenlock limestone, Dudley, England ; 

 Pseitdocrini/es oblongus Forbes (partim) of the Wenlock limestone, 

 Dudley, England; and A. clcgans Hall of the Rochester shale at 

 Lockport, New York, and Grimsby, Ontario. 



Apiocystites canadensis Billings. The holotype of this species, 

 which is preserved in the collections of the Geological Survey of 

 Canada, proves to be a small or young specimen of Callocystitcs. 

 The same form was later described by Ringueberg as C. tripectinatns. 

 Further details will be found under C. canadensis, page 245. 



Apiocystites imago Hall has been taken by Jaekel as the genotype 

 of Hallicystis. It is described on page 216 in this memoir. 



Apiocystites (?) tecumseth Billings. Through the courtesy of 

 Professor Whiteaves the writer has seen the original " fragments of 

 the column " described by Billings. The " detached plates " appear 

 to be no longer in existence. 



