408 BULLETIN 15 8, UNITED STATES NATIONAL MUSEUM 



caudal rami large, and laminate; fourth leg 3-segmented, with five 

 spines and no seta. Total length, 8-8.5 mm. 



Male. — Carapace more than half the entire length, as wide as long ; 

 fourth segment wider than genital segment and somewhat narrowed 

 anteriorly; genital segment barrel-shaped, without posterior lobes 

 or leg rudiments. Abdomen as long as genital segment, 2-segmented, 

 the segments equal in length and width; maxilliped Avith powerful 

 end claw shutting down against a bony plate on the basal segment, 

 thus making a strong clasping organ. Total length, 5-5.5 mm. 



Figure 255. — a, Caligus ionito: 

 Female, dorsal ; &, female, 

 fourth leg 



FiGDRE 256. — Caligodes meg- 

 acephalus: a. Female, 

 dorsal ; i, female, fourth 

 leg 



Remarks. — This species is very lively and can move about over the 

 skin of its host with great agility. In an aquarium the female 

 quickly sloughs off her eggs, and both sexes crawl out of the water 

 and remain there until killed by drying. 



Genus CALIGODES Heller, 1865 



Carapace only one-fourth the entire length or less; frontal plates 

 with lunules ; fourth segment narrow and elongated, forming a waist 

 connecting the carapace with the genital segment. The latter is 

 acorn-shaped and prolonged at its posterior corners into processes 

 as long as the abdomen, tapered and bluntly pointed. Abdomen 1- 

 segmented, narrow and longer than the genital segment. First and 

 fourth legs uniramose, second and third legs biramose; fifth legs 

 lacking; furca large and prominent; antennae and mouth parts 

 similar to those in Oaligus. A single species in the present area. 



