new Parasitic Copcpods on Fish. 79 



This animal resembles very much B. scomberesocis, Kr., 

 but after the examination of a number of specimens I believe 

 it to be distinct, chiefly distinguished by the character of the 

 " frontal processes " and the structure of the claws on the 

 outside of the outer branches of the true legs, which here are 

 strongly dentate, so markedly so that it appears impossible 

 that " Kroyer " could have omitted to note the fact, espe- 

 cially as he makes such a point of the curious spur found at 

 the end of each of these claws ; the single specimen from 

 which his description is taken was found in the tropical 

 Atlantic, those of mine in the Indian Ocean and on different 

 kinds of fish. 



Female. — Body elongate. Cephalothorax five-partite ; 

 first segment much broader than long, convex above ; third 

 segment very globose in shape, projecting considerably 

 dorsally as seen from the side (PL III. fig. 1 a). First segment 

 rounded in front, giving off the frontal plates by narrow 

 pedicles a short distance on each side of the middle line, 

 where the frontal border is deeply cut out, presenting a fossa 

 and a semilunar process as described by Kroyer *. 



The frontal plate bears on each side on its anterior edge 

 about fourteen delicately ciliated setse ; the inner two are 

 large and curve over the central fossa, the outer three are 

 longest and straight, directed outward ; there are also from 

 the upper surface three slender bristles, directed forward, 

 placed nearly equidistant from one another, the outer being 

 the shortest and most slender ; on the dorsal surface on each 

 side of the central fossa are two horny processes with strong 

 muscular attachments, each bearing three very short obtuse- 

 ended bristles of about equal length, pointing forward ; 

 these appear to be shorter and thicker than those of B. scom- 

 beresocis , Kr. 



Anterior antennae, long, slender, three- jointed, minute 

 hairs at the joints and a bunch at the end of the terminal 

 joint. 



Posterior antennas Particulate, each antenna folding on itself; 

 the second joint is of peculiar structure, it terminates in two 

 short crenate processes, between which are three small hairs ; 

 on the inner border is a tubercle with a strongly dentate surface, 

 the whole inner face of the limb being covered with minute 

 teeth. Hamulus placed laterally; it is two-jointed, the basal 

 joint being broad and flattened, the second of equal length in 

 the form of a strong claw, with a plumose appendage at its 

 base. 



* ' Bidrag til Kundskab,' 1803, pp. 217-219. 



7* 



