Japanese Tiicladida Maricola. 41 



They seem undoubtedly to content with the crushed remnants of 

 food which may be floating in the water, or remaining between 

 the spines of the segments, after feeding of the host animal. On 

 the whole they are, as mentioned by Wilhelmi, best regarded as 

 commensal form. 



Over 50% of Limulus longispina are always infested with a 

 large number of Ect. limidi which lives attached chiefly to the 

 proximal segments of the cephalothoracic appendages and to the 

 gill-books, much as does the other ectoparasitic Bdellourid-species. 

 According to Professor Kishinouye's statement they occur in large 

 numbers confined to the three hindermost pairs <>f the cephalotho- 

 I'acic appendages, without wandering to the gills. However, my 

 own ol)servation, which is based upon Limulus collected by myself 

 at Yobimatsu, in the province Bizen, shows l)eyond doubt the 

 occurrence of the worms on the gill-books and other parts. They 

 are not confined to the legs only. When present, they are very 

 abundant, numbering more than one hundred in two specimens of 

 Limulus examined. 



Bdelloura and Syncoelkl'mm all deposit their cocoons on the 

 gill-lamillae of their host, Limulus. Bd. Candida seems to show 

 no preference for a particular region of the gill-books, but scatters 

 its cocoon over the whole ventral surface. Bd. propinqua selects 

 the basal, or proximal region of the leaf, while Sy7i. pellucidum 

 prefers a small area near the edge, just lateral to a small marginal 

 callosity which forms a brown line with the callosities of the 

 adjacent leaves when the gill-book is closed. These Limulus- 

 infesting worms also differ in their time of breeding. Bd. Candida 

 ■oviposits during May and early June, Syncoelidium in the later 

 part of July; Bd. propiyiqua appears to breed at the same time as 

 the latter. I have not Ijeen able to discover the breeding time of 

 jFJcL limidi, but egg-laying seems to take place on the gill-lamellae 

 of the host during Jul}^ because I have found the half-grown 

 young of the parasites in abundance on the gills in the early part 

 of August. 



As stated by Wilhelmi (69, 70, 71), it seems probable that 

 the passage of the parasites from one crab to another can occur 



