212 D. Echinodermata. 



Homolampas , it is compact ; there are four genital openings enclosing a distinct 

 madreporic body, the sutures of the genital plates are obliterated, the genitals are 

 equally developed. The five or six ambulacral suckers near the abactinal pore are 

 more powerful with small sucking disks, the other suckers rapidly becoming more 

 slender towards the ambitus. These large ambulacral suckers form a rudimentary 

 petaloid area much as in embryo Spatangoids, but not by any actual petaloid ar- 

 rangement of the pores . 



Genicopatagus gen. nov. This genus has striking affinities with Holaster, Cardiaster 

 and Toxaster ; the ambulacra , as in Toxaster are all slightly sunken , but the 

 structure of the ambulacra is like that of Cardiaster , while in outline it recalls 

 Holaster. In the structure of the ambulacral system of the actinostome Genico- 

 patagus is closely related to Palaeopneustes ; it differs from it in having the odd 

 ambulacrum rudimentarily petaloid like the lateral ambulacra, also in having the 

 uniformly -sized plates composing the ambulacra above the ambitus continued to 

 actinostome. A similar uniformity of structure in the plates composing the inter- 

 ambulacral areas of the actiual and abactinal region also distinguishes this genus 

 from Palaeopneustes. The position of the anal system is similar to that of Palaeo- 

 pneustes ; but while having the actinostome of that genus and its general facies, it 

 has not its stronglymarked Spatangoid actinal surface, having no actinal plastron, 

 and an abactinal system , which while not disconnected is yet made up of large 

 genital plates in striking contrast to the compact apical system of Palaeopneustes. 

 The madreporic body covers the greater part of the right anterior genital plate. 

 The most striking feature is the small number of coronal plates composing the 

 test, particularly in the interambulacral areas." 

 Linopneustes subgen. nov. (gen. Palaeopneustes]. "Differing from Paleopneustes in 



having both a peripetalous and a subanal fasciole. 



Cionobrissus gen. nov. j>This genus is specially interesting, forming as it does a tran- 

 sition between the Brissina and the Pourtalesiae. It has the facies of the former, 

 resembling such forms as Brissopsis, but having retained somewhat the cylindrical 

 form of the Pourtalesiae, and also possessing a rudimentary anal snout immediately 

 below the anal system, so characteristic of the latter family, and of which the beak 

 of the subanal plastron in Echinocardium and the like is perhaps the first trace, or 

 of which the well defined area enclosed by the subanal fascicle is the first rudiment, 

 and which in the Pourtalesiae takes so extraordinary a development as an anal 

 snout. This characteristic feature of the Pourtalesiae of a subanal fasciole run- 

 ning round the base of the anal snout is combined in Cionobrissus with a peripe- 

 talous fasciole of the Brissina, and ambulacral petals recalling those of Macio- 

 pneustes from the presence of large primary ambulacral tubercles in the inter- 

 ambulacral areas within the peripetalous fasciole. The groove of the anterior 

 ambulacrum extends to the actinostome, but is far less marked than in the Pour- 

 talesiae, and the actinal surface is not flattened but arched , as is generally the 

 case in that family, the actinal keel forming a prominent rounded keel extending 

 from the actinostome to the extremity of the anal snout. 



Moiropsis gen. nov. This genus has, like Moira, a peripetalous fasciole forming a 

 seam immediately on the edge of the petals ; it has also, like it and other Schiza- 

 steridae, a well developed latero-anal fasciole, the odd anterior ambulacral petal 

 well limited and similar to the others, and the petals sunken. This genus is inter- 

 mediate between Moira and Schizaster, and shows that the affinity of these genera 

 is far closer than had been suspected. 



Agassiz gibt die Zahl alter jetzt bekannten lebenden Echinoideen auf 297 Arten 

 an, welche sich auf 107 Gattungen vertheilen. Die Zahl der bekannten lebenden 

 und fossilen Gattungen betragt zusammen 225 mit 2300 Arten. 



