P11Y],L01'()D CRUSTACEA 



47 



more or less produced. The 2nd antennae of the 9 not very rarely bent or folded, and nar- 

 rower than in S. s. simplex; sometimes produced into an obtuse point at the inner side of the 

 end. The g'ill of the last legs of both sexes is perhaps a little narrower than in the typical 

 form. The specimens collected by I'rofessor Hutchinson on the different dates differ greatly 



Figure 10. — Strcplocephalns simplex arabicns. A, head of Feb. $ from above (X 12). B, head of Dec. 2 

 from in front (X 7.4). C, left 2nd antenna of Feb. 9 (Xl2). D, end of abdomen of Feb. $ from above. 

 E, abdomen and egg sac of Feb. 9 from right side (X 12). 



in size, those of I-'ebruary measuring al)out 23 mm. f(ir tiie i $ and 20 mm. fur the 2 9. 

 The specimens taken in December, however, are the smallest se.xually mature specimens I have 

 ever seen reported for the genus, measuring only about 9 mm. for the largest $ S , and as 

 little as 6 mm. for 9 9 carrying eggs. In other respects they are precisely like the larger 

 specimens. 



