CLASSIFICATION. 45 



4. Patiria, Or. — Body pyrnniidal, coriaceous, five-rayed ; ossicula of the oral surface 



with uniform radiating groups of small spines ; those of the dorsal surface of two 

 kinds, the one crescent-shaped, with series of small bundles of spines, the others 

 bearing irregular round bundles of spines between them. P. coccinca, Gr. 



5. SocoMiA, Gr. — Body depressed ; rays elongate, formed of imbricate plates ; the 



margins broad, the upper and lower series of ossicles separated by a groove. 

 S. paradoxa, Gr. 



Miiller and Troschcl proposed a new classification of fifty-five species of Astcriadac 

 contained in the Berlin Museum,^ this was afterwards amended by the introduction of 

 other genera ; these memoirs formed the Prodrome of their ' System der Asteriden,' ^ which 

 now constitutes a standard work upon the Astkriad^e. As this important monograph is 

 not much known in England, no apology is necessary for giving the following translation 

 of the synopsis of the families and genera contained therein. 



SUMMARY OF THE FAMILIES AND GENERA OF THE ASTERIADtE. 



First Family. 

 Four rows of tentacula in the ambulacral avenues. With a vent. 



1 Genus. — Asteracanthion, M. and T. = Stellonia, Nardo; Uraster, Ag. 



Rays long, many rows of spines near the ambulacral areas on the under side ; the 

 whole of the upper surface of the body and rays covered with blunt or pointed spines, 

 either scattered singly or grouped toge- Fig. 20. 



ther into tufts, and arranged more or less 

 regularly in rows. The integument be- 

 tween the spines naked, showing the 

 basis of the spines. In the naked skin 

 many tentacule-pores. Pincers-like pedi- 

 cellarise, supported on soft stems, either 

 encircling the basis of the spines or „ .. , , . , , , ,. ,, ^ -p > ^ 



'-' ' Portion of a ray of Astropectenpolyacanthus, M. and 1. A, under 



scattered between them, or both'; some surface ; S, the upper surface of the ray. 



likewise on the borders of the avenues. Vent subcentral. 



1 ' Monatsbericht der Konigl. Akad. der Wissenschaft,' Monat, April, 1840. 



2 'System der Asteriden mit Zwolf Kupfertafeln, Braunschweig,' 1842. 



