86 Mr. P. W. Bassett-Smith on 



the width of the opening being less than the length of the 

 branch. First perceopod : the palm-joint is provided with 

 three small simple claws of equal length ; a fine hair at the 

 angle and three long plumose setae from the under border. 

 Third perceopod carrying the two branches some distance 

 apart, the first joint of the outer branch having on the outer 

 side a single short spur, the second having three, with four 

 plumose hairs on the inner border. Hamulus small, claw 

 slightly bent. Fourth perceopod three-jointed, bearing at the 

 extremity three curved simple claws, the outer being slightly 

 the longest ; on the centre of the inner border is a fourth, and 

 from the end of the penultimate joint a fifth slightly shorter. 



The genital segment is elongated, narrowing gradually 

 anteriorly, broadest in the centre, slightly narrower and 

 rounded posteriorly. Abdomen rather long, equal to the 

 length of the last segment, divided into two parts, more or 

 less well marked, of about equal lengths. 



Caudal plates longer than broad, bearing three terminal 

 plumose hairs and a smaller one on the outer border. 



Length 5 millim. 



Male. — Differs in its much more elongate form and oval 

 genital segment ; the terminal hook of the posterior antennae 

 is very small, but that of the hamulus anterior is very long 

 and strong ; the basal joint of the second maxilliped carries 

 on the inner border a double- crowned tubercle, to which the 

 point of the second joint approximates ; the caudal plates are 

 longer and profusely ciliated. 



Length 3 millim. 



The species described by Heller as G. constrictus is 

 evidently a male, being very like this; but he states " the 

 lunulas are minute." 



Lepeophtheirus. 



Lepeophtheirus rotundiventris, sp. n. (PI. V. fig. 1.) 



A single female specimen of this species was obtained from 

 the gill-cavity of a species of Lutjanus at Colombo; a male 

 was found on a Serranus at Muscat : though not taken at the 

 same time, place, or on the same host, yet the occurrence of 

 the distinctive characters in both of them, especially that of 

 the fourth peraeopod, justify me, I believe, in placing them 

 in one and the same species. There is a resemblance of this 

 animal to C. brachyurus } Hell., taken at Java, but they 

 differ in important details ; the peculiarly rounded genital 

 segment and the very large last thoracic joint of this species 

 at once draw the attention of the observer. 



