322 ANNELIDA 



opsopliaj^eal nerve rings and a large ventral nerve mass wliicli is composed 

 of about six fused pairs of ganglia and sends off numerous nerves. No 

 special sense organs are present. The animals are hermaphrodite. The 

 testes are paired, branched organs which are joined on each side by two 

 vasa deferentia with a lateral sperm sac; tbis opens to the outside by a 

 marginal pore near the middle of the body. Two ovaries are present ; the 

 ova are collected in a median uterus which communicates with the rectum. 



The class includes over 70 species and 2 genera. 



Myzostoma F. S. Leuckart. With the characters of the class: 

 numerous species. 



M. glabrum F. S. Leuck. Body nearly circular, 4 mm. long, with 10 

 pairs minute protuberances; parapodia short; cloaca dorsal: Europe, on 

 Antedon rosacea, attached to the oral plates. 



M. cubanum McClendon. Diameter 1.7 mm.; thickness .08 mm.; 

 dorsal surface flat, with 10 pairs of short conical cirri; ventral surface 

 convex; parapodia prominent; suckers absent: West Indies, from 

 crinoids off Havana. 



