THE COPEPOD GENUS PARANTHESSIUS — ILLG 419 



esses of the integument are placed on the distal lateral corners of 

 the middle segments of the endopodites of the first and second legs. 

 These processes are nearly as highly developed as those described for 

 the males of the other species of the present collection. In the third 

 and fourth endopodites, there are thornlike, short, spinous projections 

 in the corresponding position, but these do not show the prolongation 

 into long outgrowths like those of the first two legs. The terminal seg- 

 ment of the fourth endopodite is an identifying structure in this spe- 

 cies (fig. 36, L) . The edges of the segment are nearly parallel. Two 

 small thornlike processes (spinules or denticles) on the lateral margin 

 are characteristic. The more proximal spinule is placed at a point 

 two-thirds the length of the margin from the base of the segment. 

 The distal spinule is at the base of the terminal spine. 



The fifth leg bears a resemblance to that of P. saxidomi in the in- 

 flation of the posterior proximal margin of the free segment. How- 

 ever, the terminal spine of this species is twice the length of the seg- 

 ment (in P. saxidomi the spine is little more than one and one-half 

 times the length of the segment) . As in the other species, the spine 

 is the more posterior outgrowth of the free segment. This spine of 

 P. tivelae^ further, exceeds the accompanying seta by one sixth of 

 its own length (fig. 36, M) . 



The caudal rami are about five and one-half times as long as wide 

 (fig. 36, H). The lateral proximal seta is inserted slightly short of 

 half the distance from the base to the tip of the ramus. The most 

 medial terminal seta is longer than the lateral apical seta. The two 

 central setae of the four at the tip of the ramus are jointed at their 

 bases. The longer of these two is about two and one-half times 

 the length of the ramus. No seta of the caudal rami exhibits cilia- 

 tion of its margins. The total length of the body, excluding the 

 caudal setae, is 1.3 mm. 



Mx\le: The shape of the body and the segmentation present the 

 usual dimorphism characteristic of this group of copepods. The 

 cephalic appendages correspond to those of the female. The basal 

 segment of the prehensile maxilliped bears a weakly produced spi- 

 nous projection at the posterior medial corner. The length of the 

 second segment is roughly twice the width. A simple row of con- 

 spicuous spinules forms a border along the medial margin of the 

 segment. The long claw comprising the terminal joint is twice the 

 length of the second segment (fig. 35, 1) . 



The swimming legs conform more closely to the female type than 

 is usually the case in the other species in the present collection. There 

 is an accentuation of the spinous nature of the marginal fringes of 

 the basipodites and the spinous processes of the endopodites are 

 somewhat longer and more robust. 



