BY E. P. HALLMANxV. 405 



to those of the main skeleton; also, there occur, in the dermal 

 membrane, microscleres in gi-eat abundance, and the most numerous 

 of these are the smaller anisochelas, the isochelae, and the smaller 

 sigmata, wliile the larger sigmata are the rarest. 



Spicules, —(a) Subtylostyli; with elongated oval heads, nar- 

 rower than the middle of the shaft; typically straight, though 

 often, in slight degree, variously curved; gradually sharp-pointed; 

 slightly fusiform, with the apical half of their shaft of greater 

 average stoutness than the basal. Length, 250 /x to 305 /x: 

 maximum stoutness, 9 or 10 /x. 



(6). Larger anisochelse; 40-45 /x long, 13-17 /x wide;* 15-18-5 /x 

 broad; occurring singly and in rosettes. The upper alse and palm 

 are of equal length, approximately one-half that of the spicule; 

 the upper tuberculum is 7-5-11 /x long, and about one-fourth of 

 this in breadth; the distance between the free ends of the two 

 palms is about 15 /x. Rosettes appear to be rare and always 

 composed of comparatively very few chelae; they were found only 

 in the dermal membrane, and the greatest observed number of 

 spicules composing any one of them was eight. 



(c). Smaller anisochelse; 18-22-5 /x long, 6-7' 5 /x wide, 4*5-8 /x 

 broad; occurring singly. The upper alte and palm are about 

 equal in length, which is approximately three-tifths that of the 

 spicule; the distance between the free ends of the palms is about 

 3-5 /x. 



(o?). Isochelae palmatse; 7-5-12 /x long, at most 3 /x wide, and 

 3-3-5 /x broad. These are the most abundant of the microscleres, 

 at any rate in the dermal membrane. 



(e). Larger sigmata; 72^ to (rarely) 20 /x in length from bend 

 to bend; and, at most, slightly over 6 /x in stoutness. 



(/). Smaller sigmata; very slender; varying in length from 

 15 /x to 35 /x. 



* In using, for convenience' sake, the ordinarily synonymous terms luide 

 and broad in order to express the t\To principal transverse dimensions of a 

 chela, I imply by the former the maximum cross-measurement of the 

 spicule as seen in profile, or, more precisely, the distance from the free 

 or distal end of the (in case of anisochehe, major) palm to the posterior 

 edge of the shaft; and by the latter, the maximum cross-measurement of 

 the spicule as seen from the front. 



