8 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 122 



Caudal ramus (fig. 45) resembling that of female but much shorter, 

 28/x X 18/i, or 1.55 times longer than wide. 



Dorsal surface of body with few hau's (as in figs. 43, 44) ; ventral 

 surface of urosome almost completely lacking ornamentation. Ratio 

 of length of prosome to that of urosome 1.43 : 1. 



Rostral area like that of female. 



Fkst antenna similar to that of female but with 3 aesthetes added, 

 so that formula is 4, 13+2 aesthetes, 6, 3 + 1 aesthete, 4 + 1 aesthete, 

 2 + 1 aesthete, and 7 + 1 aesthete. Second antenna resembling that 

 of female but inner margin of second segment with a row of dentiform 

 spinules (fig. 46). 



Labrum, mandible, paragnath, first maxilla, and second maxilla 

 similar to those in female. Maxilliped (fig. 47) elongated and slender, 

 4-segmented, assuming that proximal part of claw represents a fourth 

 segment. Fii'st segment unarmed, second with two setae and rows 

 of spinides on inner surface, third short and unarmed. Claw slender 

 and gently recurved, 127/x along its axis (including terminal lamella), 

 with faint indication of division about midway; two unequal setae on 

 proximal part of claw. 



Legs 1-4 as in female except for endopod of leg 1 where formula for 

 last segment (fig. 48) is 1,1,4, instead of 1,5 as in female. 



Leg 5 (fig. 49) with elongated free segment, ISyux 6m, lacking a basal 

 expansion. Two terminal setae Sjj. (inner) and 24/x (outer). 



Leg 6 (fig. 50) a posteroventral flap on genital segment bearing 

 two naked setae IS/j. and 22^ long. 



Spermatophore (fig. 51) moderately elongated, 127 jjlx 56^ (wdthout 

 neck), often attached to female in pairs. 



Color in life in transmitted light similar to that of female. 



Etymology. — The specific name rhadinus, from the Greek word 

 pQ!5ij^6s = slender, refers to the slender form of the body, of the first 

 and second antennae, and of the maxillipeds in this species. 



AIeTHOD OF COLLECTION AND RELATION TO HOST.- — LichomolgUS 



rhadinus was recovered after washing the coral in alcoholized sea 

 water within a few hours after collection. In contrast to the recovery 

 of Xarifia diminuta and Bhynchomolgus coralloijhilus, where the great- 

 est numbers of specimens were found after allowing the coral to 

 remain in alcoholized sea water overnight or after crushing the 

 coral, all L. rhadinus were obtained in the first washings and none 

 were found in the second washings after an overnight delay or after 

 crushing. This suggests that L. rhadinus lives on the surface of 

 the coral whence it is easily dislodged, rather than in the polyps. 

 Comparison with related species. — The distinctive form of the 

 mandible in L. rhadinus sets it apart from almost all of the other 

 70 or more species already described in the genus. Only five species 



