80 PROCEEDINGS OF THE NATIONAL MUSEUM. tol. 53. 



the others become paratypes with Cat. No. 12327, U.S.N.M. A single 

 female, without a head, was obtained from the same host in the 

 Florida Keys and was cleared in clove oil to obtain the internal 

 anatomy. 



/Specific characters of female. — Specific characters the same as the 

 generic, with the addition of the following details: Cephalothorax 

 and anterior thorax segments all very soft and fleshy, the cushion 

 processes much inflated, forming on the dorsal surface three longi- 

 tudinal ridges, the central one the cephalothorax proper, the others 

 the lateral processes. 



On the fourth segment the lateral processes are conical and extend 

 backward on either side of the neck. That portion of the neck which 

 is inclosed in the bulbus arteriosus is also soft, but becomes gradu- 

 ally chitinous and where it passes out through the wall of the artery 

 is armed with two or three branched chitin horns, which are buried 

 in the adjacent tissue. The neck then softens again before it joins 

 the trunk and is twisted somewhat upon its long axis, but just how 

 much it was impossible to tell, because the two heads were packed 

 so tightly together inside the bulbus arteriosus (see ''''Remarks'''' 

 below). The anterior end of the trunk points forward toward the 

 fish's mouth and the abdomen is turned outward away from the 

 bulbus arteriosus, so that when there is a parasite on both sides of 

 the fish the one is the reverse of the other. 



The long e^gg coils reach out through the gill opening and are 

 visible from the exterior when the operculum is closed; each, if un- 

 coiled, would be at least three times the length of the trunk. 



The first antennae are tv»'0-jointed and setiferous; the second pair 

 are also two-jointed and comparatively minute; they project very 

 little and the tooth of the chela is nearly as large as the claw. The 

 maxillae are attached to the ventral surface of the head at the base 

 of the mouth-tube, which can not be protruded very far, if at all; 

 each maxilla is made up of two slender joints and a long needlelike 

 claw, slightly curved. Only the first thorax joint is fused with the 

 head, and this is fairly well differentiated on the sides by the lateral 

 processes. The first and second swimming legs are close together, 

 the second pair much larger than the first; the third and fourth 

 pairs are separated by considerable intervals, each on the posterior 

 margin of its segment. In the preserved material the basal lamina 

 of every leg is heavily pigmented with black, which makes them 

 stand out prominently. 



Color (preserved material), head, neck, and trunk a light yellowish 

 gray, o^gg strings orange yellow. 



Length of trunk, 3.50 mm.; diameter, 1.50 mm. Length of head 

 and neck, 2.50 mm. Length of egg coils, 4,50 mm.; diameter, 

 0.60 mm. 



{parvus, small.) 



