THE MYRIAI'ODA OF NORTH AMERICA. 193 



a depression occupying' sulcus; rough, anterior part closely obliquely 



stria te beneath, above, especially on aiiterior part, and along 1 the de- 

 pression, numerous horseshoe-like depressions. Repugnatorial pore 

 large, placed on anterior part, a dee]) suleus behind. Anal segment 

 slightly angulated, not passing valves; anal valves scarcely margined, 

 sparsely punctate; anal scale almost transverse. Legs extending 

 slightly beyond sides of body. Segments, female, 51-53 j male, 51. 



Male: Less robust than female ; eox;e of second pair of legs large, coxae 

 of other legs not produced; femur with a slightly swollen ovate knob: last 

 tarsal joint with an elongate sucker; sixth and seventh segments swol- 

 len beneath; ventral plate of copulation foot convex, one-half as high 

 as foot, apex bind; anterior copulation foot short and heavy, outer 

 part plain, curling' around inner, end slightly pointed, inner part heavy. 

 its inner margin slightly concave, a small wing on its anterior surface; 

 posterior copulation foot somewhat hook-like, its end rounded and 

 slightly bifid; on the inner side are three lobes; the first is large and 

 moderately flat, with its entire surface granulated ; the second is spine- 

 like and arises just above the first; it is twisted, tapering, with its outer 

 surface very rough; it ends near the beginning- of third, which is flat 

 and bent basal wards, its end concave. Length, 40-50 min ; width, 4-5""". 



This species seems to bear little resemblance to any other from Amer- 

 ica. It probably comes nearest to 8. flow linen; as shown by the form of 

 the posterior copulation foot, but the rest of the copulatory organ is 

 entirely different. 



In the collection is one specimen labelled u Surinam,'' and a very large 

 number in another vial without any locality, but which 1 suppose are 

 from the same place. 



5. Spirobolus caudatus Newport. 



<-iiHtllnx Newport. Ann. :nil May. Nat. Hist., 1'lill. l,x| | (l)cmcrara); 

 arlion //* Saiissun-. Linn. I-'.nt.. ;>31. 18r>)(,s7. 



Segments, male, 51-53; female, 51-50; ocelli 40-55, in 0-S series. 

 Male: Coxa- of none of the legs noticeably produced or any other mark- 

 ings of note about the legs. Ventral plate of copulation foot higher than 

 anterior part of first foot, but not so high as posterior part; its end 

 rather suddenly pointed, slightly truncate. Anterior or inner part of 

 anterior copulation foot pointed; end of posterior part rather blunt and 

 swollen. Posterior foot long and slender, curved outwards and back 

 wards, theonlypart of copula! ion foot projecting out of opening; bifid, the 

 upper branch compressed, especially towards the end which is slightly 

 sinuate, its lower angle \\ ith a short, slemlerspine: lowerbranch lanceo- 

 late, not as long as upper, depressed, sides very thin and transparent. 

 edges entire or very slightly sinuate. Ventral part of the anterior half of 

 seventh segment produced into a blunt, triangular lobe. 



In the collection are a number of specimens which were obtained by 

 the I'. S. Fish Commission at St. Thomas. 

 1>0'J7 No. 40 - 13 



