214 Twenty-fourth Report on the State Museum. 



This is a small gracefully formed species ; it differs from the H. 

 sim^plex {== H. canadensis Billings^ Decade iv, Canadian Organic 

 Hemains, PL iv, f. 5) of the same locality, in size, in the structure of 

 the calyx, and in the form and structure of the arms. 



Formation and locality. Hudson-river shales, Cincinnati, Ohio. 

 From Mr. W. H. Thomas. 



Genus — AGELACEINUS Yanuxem. 



Agelaceinus [Lepidodiscus] Cincinnatiensis Bcem. 



F. KoEMER, Verb. Katurh. ver. fiir Klieinl. und Westph., Yol. viii, p. 372, t. 3, figs. 

 3«, h. 1851. Bronn's Lethea Geog. Vol. ii, pp. 275-277, t. 4, fig. 6. 



Plate 2, fig. 7. 



This species, described by Hcemek, is from the Lower Silurian 

 shales of the age of the Hudson-river group at Cincinnati. 



It has a moderately convex disc, usually with a diameter of 

 one-half to three-fourths of an inch, though it sometimes reaches 

 a diameter of nearly one inch, which is about the size of the one 

 figured by Dr. Rcemek. The smallest specimen identified with this 

 species has a diameter of less than one-fourth of an inch. 



The disc is composed of numerous imbricating scale-like plates, 

 the rays all curving, four sinistral and one dextral, the interradial 

 areas composed of large plates; the mouth, anal or ovarian aperture, 

 situated subcentrally in the largest area and enclosed between the 

 dextral and one of the sinistral rays, and surrounded by a pyramid 

 of small triangular plates. 



This species is more commonly found adhering to the valves of 

 Strophomena alternata, though it sometimes occurs attaclied to the 

 shell of Modiolojpsis and to coralline masses. 



Agelaorinus pilefs n. sp. 

 Plate 2, figs. 8-10. 

 Body subglobose or globular bell-shaped, attached by the smaller 

 extremity, which is composed of small squamiform plates. Rays 

 rising from the top of the dome, and curving gently down the sides : 

 four sinistral and one dextral ; the dextral and one sinistral surround 

 the posterior interradial space. The rays are formed of two ranges 

 of lanceolate plates, their ends pointed and interlocking over the 

 arm-grooves ; their bases originating in a transverse pyramid formed 

 by the union of two bifurcating or V-shaped plates, one on each side 

 of the base of the anterior ray, and a single shield-shaped plate which 

 is situated at the upper extremity of the posterior interradial area. 

 The extremities of the rays appear to have been subsessile. The late- 

 ral arms originate in pairs, the anterior arm being separated from 

 them by the V-shaped plates. 



