216 



Of several individuals obtained all were females. 



Tlie fiivorite place for the parasite to fasten is immediately back 

 of the pectoral fins of its host. It often left the fish and swam 

 about the tank, then returning fastened to any part presented, and 

 crawled to its place near the pectoral fins. I have reason to believe 

 that it may also occupy the gill cavities. I have left individuals 

 alone in a glass of water five days without any apparent loss of vigor. 



The blood circulation is very well seen at many points, especially 

 about the eyes and at the margins of the abdominal lobes. The 

 current passes down the inner margin, around the apex and up the 

 outer margin; at intervals along the outer edge lateral currents are 

 given ofi", which seem to occupy blood vessels jiroper. The cor- 

 puscles are small, apparently spherical and not numerous. 



The striped muscular fibers moving the legs and antennae can be 

 very clearly made out with an inch objective. 



The species of this genus are indeed microscopical and zoological 

 gems whose value is not enhanced by their rarit3% 



