﻿2l6 SMITHSONIAN MISCELLANEOUS COLLECTIONS [VOL. 47 



but their preservation is such that nothing can be added to the de- 

 scription and illustrations given by Hall except the structure of the 

 anal area. This is composed of 2 circles of pieces — an outer of many 

 small plates and the pyramid. 



Formation and locality. — In the upper portion of the Coeymans 

 limestone of the Lower Devonic, at many places in eastern New 

 York. It has not been found, to the writer's knowledge, south of 

 New York. 



Cat. numbers 10.557, 26,923, 33,202, 35,075, 35,076, U. S. N. M. 



Hallicystis Jaekel 



Apiocystites Hall (not Forbes nor Hall, 1852), Twentieth Rep. N. Y. 



State Cab. Nat. Hist., rev. ed., 1868 [1870], p. 358. 

 Haliicystis Jaekel, Stammesgeschichte der Pelmatozoen, Berlin, 1, 1899, 

 p. 287. 



Definition. — Apiocystinae ? with the theca elongate balloon-shaped, 

 base not invaginated, and with 5 rows of 4 plates arranged as 

 follows : 



Basal row has plates 4, 1, 2, 3. 



Second row has plates 5, 6, 7, 8, 9. 



Third row has plates 10, 11, 12, 14. 



Fourth row has plates 16, 17, 18, 13, 19, 15. 



Fifth row has plate 20 and deltoids 21, 22, 23 double, 24. 



Anus prominent, bounded by plates 7, 8, and 13. Pyramid en- 

 closed by a complete circle of minute plates. 



Pectinirhombs normally situated, discrete, with few dichopores. 



Ambulacra 4. As all the specimens are internal casts, the details 

 of the exterior cannot be ascertained. 



Genotype, Apiocystites imago Hal.1. 



This genus differs from Apiocystites in having 5 deltoids instead 

 of 1, but otherwise seems to be closely related. Only two species 

 are known. 



HALLICYSTIS IMAGO (Hall) 



Apiocystites imago Hall, Twentieth Rep. N. Y. State Cab. Nat. Hist., 

 rev. ed., 1868 [1870], p. 358, pi. 12, fig. 12; pi. I2A, fig. 9. 



Hallicystis imago Jaekel, Stammesgeschichte der Pelmatozoen, Berlin, 1. 

 1899, p. 288. 



Rare in the Niagaran dolomites about Chicago, Illinois. 

 The diagram of plates (figure 24) is based on specimen 35,060, 

 I*. S. \. A I., and on material in Dr. B. E. Walker's collection. 



