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BULLETIN 2 01, UNITED STATES NATIONAL MUSEUM 



have two or three grooves and ridges, but the sixth abdominal somite 

 has otherwise no special ornamentation or sculpture. (2) The cara- 

 pace is produced into an acute triangular rostral plate with a bluntly 

 rounded apex. (3) The antennal scale is seven times as long as broad. 

 (4) The endopod of the third to the eighth thoracic limbs has the sixth 

 joint divided into four to six subjoints. (5) The inner uropod has a 

 row of five spines on the lower margin near the statocyst, (6) The 



telson (fig. 88) is narrowly triangular in 

 shape, two and a half times as long as 

 broad at the base, apex narrowly truncate, 

 almost rounded, and armed by two pairs 

 of spines, the outer pair twice as long as 

 the inner pair and considerably stouter; 

 the lateral margins are armed with about 

 27 large spines extending throughout the 

 entire length of the margin and increasing 

 very conspicuously in length toward the 

 apex; on the distal three-quarters of the 

 margins there are small spines between the 

 large ones; proximally only two or three 

 small spines between the large ones, but 

 the number gradually increases so that dis- 

 tally there may be 10 to 12 small spines 

 between the larger ones. 



The present material is defective and 

 much damaged but appears to agree very 

 closely with Dershavin's description. The 

 telson has many more small spines between 

 the larger spines on the lateral margins, 

 especially distally, than would appear 

 from the figure given by Dershavin. Since 

 no details are given in the description it is 

 a little difficult to decide how much im- 

 portance should be given to this point. In 

 other characters, antennal scale, rostral 

 plate, inner uropods, and the folds on the 

 abdominal somites, these specimens agree 

 very closely with A. stelleri, and provisionally at any rate I refer them 

 to this species. The material is so badly damaged that the drawing of 

 the telson here given had to be made from a telson that had evidently 

 at one time been damaged and then the damaged part regenerated. I 

 have had to guess the breadth distally and may possibly have drawn 

 it too narrow in proportion to its length. 



Unfortunately none of the males is complete, and I am unable to 

 describe the form of the fourth pleopod in that sex. The species is 



Figure 88. — Acanthomysis stelleri 

 (Dershavin): Telson, X 22){. 



