216 TWENTY-FOURTB REPORT ON THE StATE MuSEUM. 



plates. Rays straight, broad at base, narrowing toward the outer 

 extremities, which are obtusely rounded ; composed of proportionally 

 large plates. 



Interbrachial areas distinct. Ovarian aperture situated centrally 

 in the largest area. 



This species is represented by two individuals, the largest of which 

 is very entire, and presents all the parts in a very satisfactory condi- 

 tion. The perfectly straight rays are peculiar, and do not admit of 

 the probability of its being the young of any of the forms with curved 

 ra}'S; since young specimens of AgelaGrinus Cincinnatiensis of but 

 little larger growth have the rays distinctly curved. 



This form is similar to the Hemicystites parasiticus of the Niagara 

 group, having the sides more abruptly elevated than the ordinary 

 forms of AaELACRiNUs, while the rays are straight and prominent. In 

 consideration of these and other characters mentioned, I designated 

 the Niagara species under the name Hemicystites, while Dr. Rgemer 

 and others following him, have placed the same under Agelacrinus. 

 I am, nevertheless, disposed to regard such forms as generically dis- 

 tinct. 



Formation and locality. In shales of the Hudson-river group, Cin- 

 cinnati, Ohio. Parasitic on Strojphomena alternata. 



Genus — LICHENOCRINUS ^(?^.^m. 



Bodies parasitic on shells and other foreign substances. Form dis- 

 coid or depressed-convex, with a proboscidiform appendage rising 

 from the center. Disc composed of an indefinite number of poly- 

 gonal plates, and apparently having no distinct mode of arrange- 

 ment. Proboscis perforate, and in the known species formed of five 

 ranges of short plates alternating and interlocking at their margins. 



The fossils for which this generic name is proposed are small para- 

 sitic scab-like bodies, usually found adhering to the smooth surfaces 

 of shells and other foreign substances. 



The two species now known are from the shales of the Hudson- 

 river group in the neighborhood of Cincinnati, Ohio. 



LicHENOOEiNus Dyeei n. sjp. 

 Plate 7, figs. 1-6. 

 Body small, discoid, depressed in the middle, with five slight ele- 

 vations midway between the center and the edge of the disc. Pro- 

 boscis strong, composed of short plates. Disc composed of very 

 small polygonal plates. Surface smooth. 



Formation and locality. Hudson-river group, at Cincinnati, 

 Ohio ; attached to the inner surface of worn valves of shells. From 

 Mr. C. B. Dyer. 



