GENEKA AND GROUPS OF THE EOHIKOIDEA. 239 



obliquely so as to pass oyer the posterior face at some distance 

 below the top of the test and the periproct. 



Bjecent. Indian Archipelago, 129 fms. 



The subgeneric character is the shape and relative size of the 

 anterior ambulacrum. 



Genus Htpsopatagtjs, Pomel, 1883, Theses, p. 31. (Slightly 

 enlarged.^ 



Syn. Macropneustes, Agass. (pars). 



Test moderate and large, tumid in ovoid outline, depressed and 

 tumid dorsally, rostrated posteriorly and truncated. 



Apical system subcentral, or slightly excentric in front. 



Anterior ambulacrum in a slight groove ; pores simple. Paired 

 ambulacra either long and grooved, or shorter and broad and 

 semi-flush ; the poriferous zones slightly sunken, and the inter- 

 poriferous areas ornamented and tumid. 



Peristome excentric in front, semilunar, transverse. Periproct 

 in the posterior truncation. A peripetalous fasciole including 

 scarce or moderately close primary tubercles. 



Fossil. Eocene : Europe and Africa and Asia. Miocene : IN". 

 Africa. 



M. Pomel cites as the types H. Meneghinii and H. Amman, 

 and the Sindian species of Macropneustes become Sypsopatagus 

 speciosus, Dune. & Sladen, S. rotundus, Dune. & Sladen. 



III. Division Prymnodesmia. 



Spatangoidea with a subanal fasciole, and the plates of the 

 postero-lateral ambulacra within the fasciole modified, and their 

 pores also. Other fascioles may exist. 



Genus Micraster. 



Subgenus Brissopneustes. 

 Genus Brissus. 



Subgenus Meoma. 

 Genus Spatangomorpha. 

 Troschelia. 

 Metalia. 

 Rhinobrissus. 

 Brissopsis. 

 Subgenus Cyclaster, 

 Genus Brissopatagus. 

 Spatangus. 

 Subgenus Loncophorus, 



