332 Note on the Madreporite of Cribrella ocellata. [Jan. 26, 



Fig. 6. 



I am not in a position to state that such is the nsual arrangement 

 in Crihrella : but that such a connexion should exist even as an 

 abnormality is not without interest. Mere closure of the internal 

 aperture of the ampulla would not lead to the common asterid 

 arrangement, because of the canals (PM 2 and PM 1 ) and others with 

 similar relations, which are some distance from the aperture of the 

 ampulla. 



EXPLANATION OP LETTEKS. 

 Amp. Ampulla. 



AR. Anal " blood vascular " ring. 

 Gt. Tract of "blood-vessels" to gut. 

 Ht. " Heart " or dorsal organ. 

 M. Madreporic ossicle. 

 Oss. Ossicles in body wall. 

 PM I 



PM 1 V Pore canals of madreporite. 

 PM 2 J 



Schl. " Schlauchformiger Kanal." 

 St. Stone canal. 



SHADING-. 



Light. Connective tissue and muscle. 



Dark. Ossicles. 



Black. Epithelium of stone canal, &c. 



Cross. "Blood vascular" tracts. 



