NO. 1504. AMERICAN PARASITIC COPEPODS—WILSOX. 705 



Proboscis slender and conical; the chitin framework is quite simple 

 in construction and consists of four longitudinal plates articulated at 

 the base with the ventral surface of the carapace. They taper rapidly 

 toward the tip, where they are articulated with one another in pairs, 

 two on the ventral and two on the dorsal surface. Between these 

 plates are other shorter ones which only reach half the length of the 

 proboscis. 



Over this framework is stretched the upper and under lips. The 

 mouth opening is subterminal and horseshoe-shaped, the curve being 

 at the tip of the proboscis, while the sides extend back on the ventral 

 surface alongside the lower lip. The entire opening is heavily fringed 

 with hairs. The mandibles are slender and somewhat spatulate in 

 shape with a row of ten or twelve comb-like teeth on the inner margin 

 at the tip. 



The two pairs of maxillae are reduced to mere semicircular plates, 

 attached in the normal positions but scarcely raised above the ventral 

 surface. The first and second maxillipeds are normal, the terminal 

 claw on the latter being stout and lacking an accessory spine on ita 

 inner margin. 



The basal joints of the first pair of legs are rather swollen and carry 

 a short and blunt projection at their outer ends on the ventral surface 

 just where the terminal joints are attached. 



The exopod is much larger than the endopod, both being two- 

 jointed; the joints are- approximately equal in the exopod and the 

 terminal one carries in addition to the regular plumose setfe and spines 

 a large chitinous claw or process which is curved down tightly against 

 the end of the joint. In the endopod the basal joint is about four 

 times the size of the terminal, the latter being nearly spherical and 

 carrying a single large plumose seta on its inner margin. The second 

 and third legs are normal, save that in each the exopod bears upon the 

 ventral surface of its two terminal joints huge chitin claws similar to 

 those upon the first pair. The rami of the third legs are larger than 

 in Calujus and project well bej^ond the basal lamellte. 



The fourth legs are so rudimentary as to be entirely concealed, in a 

 dorsal view, by the sides of the fourth segment, and in a ventral view 

 by the bases of the third legs. By lifting up the latter the stumps of 

 these legs can be seen on the ventral surface of the free segment; they 

 are papillate, one-jointed, and terminate in three short setse. 



The rudimentary fifth legs can also be seen as triangular stumps 

 near the lateral margins of the genital segment, each carrying three 

 short setje. 



The furca is wanting, but in its place is a pair of chitin ridges, 



between the bases of the first maxillipeds. These start close together 



on either side of the mid line and run diagonally forward and outward 



toward the second maxillw. They are raised considerably from the 



Proc. N. M. vol. xxxi— 06 46 



