40 



can at any time easily rid itself of its visitors if so inclined. 

 The worm, however, is by no means an active species. 



Male. — In the examples of the parasite which appear to be 

 males (Plate V, fig. 1), the cephalothorax is somewhat ovate, 

 narrowed behind, and furnished in front with minute chiti- 

 nous processes like hairs. The head has a pair of rather 

 stout antennae, composed of four regularly diminishing seg- 

 ments. The edges of the last three under pressure are not 

 smooth, but have minute projections from which the setse 

 spring. The terminal segment is tipped with several setse, 

 which are longer than itself. The next two limbs arise 

 from the region between the former and the mouth, are more 

 slender, and appear to have a similar number of articula- 

 tions, but, from their softness, it is difficult to determine the 

 exact number. The exposed surfaces of the two terminal 

 segments are marked by certain microscopic serrations, which 

 have a definite arrangement. The tip of the organ has about 

 five long setse, one of which much surpasses the other in 

 length. The sides of the mouth are furnished with two 

 pairs of folded limbs, the posterior of which has its terminal 

 articulations furnished with a single strong claw. 



The cephalothorax behind the foregoing has on each side 

 three processes. The anterior consists of a short and rounded 

 basal portion, with two slender terminal processes. The latter 

 differ from each other in shape, the outer having the form of 

 a sabre-sheath, with numerous microscopic spikes along its 

 convex surface, and a tip furnished with about three setse, 

 two of which are very long. The other process is generally 

 straight, has also the microscopic spines along its outer 

 border, but there is only a single long seta on its tip. The 

 same description applies nearly in all respects to the succeed- 

 ing pair of limbs. The third pair is represented by a simple 

 conical papilla with a terminal bristle. 



The cephalothorax generally is filled with a minutely gra- 

 nular substance, except when the well-defined longitudinal 

 and transverse muscles of the body appear. Posteriorly 

 there are also two elongated translucent bodies, probably 

 the testicles (?) . Behind the posterior narrowed region is a 

 bifid caudal process with two long lateral styles. Each of 

 the latter consists of a strong basal segment, and an elon- 

 gated filiform process with traces of segmentation. 



The male is very much smaller than the female. 



Female. — In the young condition the body has a somewhat 

 ovoid figure, with a produced posterior and a blunter anterior 

 extremity, and both antennee and caudal styles can be ob- 

 served from the dorsal surface (fig. 4). In the fully deve- 



