I06 HAROLD HEATH. 



body wall in front of the proboscis and may in reality represent a 

 modified mantle, having been developed from such a type as 

 now exists in the aspidobranchs. 



Concerning the systematic relationships of this animal it is 

 difficult to speak with certainty. From the paired character of 

 the testis it appears to have been derived from some aspidobranch 

 ancestor in which there were traces of the original bilateral sym- 

 metry. In its present condition the animal is perfectly sym- 

 metrical, but it does not follow that its immediate ancestors were 

 such. Just as the modern more or less symmetrical lithodes 

 have been derived from the asymmetrical hermit crabs so this 

 species may have secondarily assumed its symmetrical condition. 



The genus may be defined as follows : 



Ctenosculuni new genus. Body globular, bilaterally symmetri- 

 cal, almost completely enveloped in a fold of the body wall. 

 Proboscis and tentacles present. Two sets of salivary glands, 

 radula reduced to one triangular tooth. Monoecious, testis and 

 ovary distinct and separate, the latter occupying the fold. Para- 

 sitic in starfish, Brisinga evermanni, Hawaiian Ids. Type of 

 genus C. hawaiiense. 



C. hawaiiense new species. With characters of the genus. 



I 



