THE MYRIAPODA OF NORTH AMERICA. 193 



a depression occupying sulcus; rough, anterior part closely obliquely 

 striate beneath, above, especially on anterior i)art, and along the de- 

 pression, numerous horseshoe-like depressions, liepugnatorial pore 

 large, placed on anterior part, a deep sulcus behind. Anal segment 

 slightly an gala ted, not passing valves; anal valves scarcely margined, 

 sparsely punctate; anal scale almost transverse. Legs extending 

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



Male: Less robust than female; coxre of second pair of legs large, cox;e 

 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 bifid; 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 basalwards, its end concave. Length, 40-50 mm ; width, 4-5 mn '. 



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

 ica. It probably comes nearest to 8. dominicw, 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 "Surinam," and a very large 

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

 from the same place. 



5. Spirobolus caudatus Newport. 



Sjiirobolus caudatus Newport. Ann. and Mag. Nat. Hist., 269, 1844 (Demerara) ; Juhis 

 arboreits Saussuro, Linn. Ent._. 331, 1859 (St. Thomas). 



Segments, male, 51-53; female, 51-56; ocelli 40-55, in 6-8 series. 

 Male : Coxa 3 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, theonly part of copulation foot projecting out of opening; bifid, the 

 upper branch compressed, especially towards the end which is slightly 

 sinuate, its lower angle with a short, slender spine; lower branch 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 U. S. Fish Commission at St. Thomas. 

 2097— No. 46 13 



