ECHINODERMATA. 



169 



maximum in the present seas. The Palaeozoic species differ from recent 

 ones in having the plates perforated by pores. No family of Star-fishes 

 has become extinct. 



No. 856. Asterias . 



From the Hamilton group (Devonian) Otsego Co., N. Y. Price, $0.50. 



No. 857. Asterias (?) 



Two specimens, showing both sides ; very perfect. From the Hamilton 

 group (Devonian). Price > $ 1 - 00 ' 



No. 858. Asterias . 



Impression on a black Permian slate (Kupferschiefer), from Riegensdorf, 

 Germany, and now in the private Geological Cabinet of Mr. Ward, Rochester. 



Price, $0.60. 



No. 859. Astropecten 



This finely preserved Star-fish (the Grenaster of Luid) was found in the 

 Calc-grit (Lias), near Whitby, England, and now belongs to the private Geologi- 

 cal Cabinet of Mr. Ward, Rochester. Size, 9x8. Price, $1.50. 



No. 860. Ophioderma Egertoni, Broderip. 



This genus differs from the Ophiura proper in 

 having four (instead of two) genital fissures in each 

 interval between the arms. This specimen is from 

 the Lias of Lyme-Regis, England, and now in the 

 Ward Museum of the University of Rochester. 



Price, $0.60. 



No. 861. Ophioderma Egertoni, Brod. 



A slab, showing 17 individuals in an unusually perfect condition. This 

 unique specimen, from the same locality as the preceding, is now in the private 

 Geological Cabinet of Mr. Ward, Rochester. Size, Price, $2.50. 



No. 862. Palseaster . 



This generic term has been applied by Professor Hall to the Silurian species 

 of Asteridce. According to Agassiz, all the Palaeozoic forms differ from the recent 

 Star-fishes in having the plates perforated by pores. This specimen is troni the 

 Hudson River group (Lower Silurian), Cincinnati, Ohio. Price, $0.30. 



No. 863. Solaster Moretonis, Forbes. 



This beautiful and well-preserved fossil seems as if it were the head of a 

 Crinoid with out-spread arms, crushed flat. A nearer inspection shows that it is 

 reaDy a Star-fish, resembling the living Tlr aster lieliantJius from the Pacific coast 

 of South America. From the Great Oolite, Windrush Quarry, Gloucestershire, 

 England. Size, 6x6. Price, $1.00. 



