MEMOIRS OF THE NATIONAL ACADEMY OF SCIENCES. 



55 



molted specimens, but in others scarcely distinguishable from the dark-brown, fiuely-shagreened 

 tegument. Behind the eyes the body contracts dorsally, as well as laterally. On the front edge of 

 the eephalothorax is an acute median spine. The six basal abdominal 

 joints are coalesced, forming a single piece, segments 3 to 6 being indicated 

 by a pair of somewhat transverse, high, well-marked tubercles (not form- 

 ing true spines as in N. dentipalpe). The four terminal segmeuts are free; 

 the terminal one subtriangular, one fourth shorter than wide. Beneath are 

 seven well-marked sterna, with lunate, dark spiracles on the sternum of 

 the second segment. 



Chelicera? (Plate XIV, fig. 3) hairy, with thebasal joint not so long as broad; 

 second joint of the same width throughout, not swollen toward the end; 

 third joint bent downward and inward at right angles, the hand directed 

 a little outward ; the movable finger as long as the hand is thick. Pedi- 

 palps (Plate XIV", fig. 3a) very long and slender, hairy, nearly twice as long 

 as the body, while in the European dentipalpe they are scarcely half as long- 

 in proportion; six-jointed (iu dentipalpe five-jointed), the basal joint sub- 

 triangular in outliue, owing to the upper edge being dilated; second a 

 little longer and much slenderer than first, and slightly curved ; third a 

 little more than twice as long as the second, very slender; fourth a little 

 shorter than third ; fifth three-fourths shorter than fourth ; and sixth 

 slightly shorter than the second, rounded at the end, being cylindrical, 

 ovate, and unarmed, though with rather stiff hairs. 



Legs much longer and slenderer than in HI. dentipalpe, with all the coxae of 

 nearly the same size, the hinder pair being a little shorter and broader. 

 First pair about twice as long as the body, with eight tarsal joints ; joints 

 four to seven, together a little longer than the terminal one; a single long, 

 stout, curved claw. Second pair nearly three times as long as the body; 

 length, 4 ram ; tarsi very long and sinuous, like a whip-lash, the last joint 

 divided into nine subjoints; the claw rather feeble ; the second joint half 

 as long as the first. Third pair of legs of the same length as the first pair ; 



tarsi eight-jointed, the two terminal joints subdivided into two joints. Fourth pair nearly three 

 times as long as the body; tarsi eight-jointed, the two last sometimes subdivided into two sub- 

 joints (iuternodes) Length, 3 m "\ 



Found under stones on the bottom of Clinton's Cave, Lake Point, Utah, in a damp place, not 

 infrequent, July 28, 1875. Quite active in its movements. Most of the specimens were apparently 

 distended with eggs. 



This is the first occurrence of the genus in America. I have been able in drawing up the 

 above description to compare our species with the European Nemastoma dentipalpe of Ausserer, 

 a specimen of which was kindly loaned me for the purpose by Mr. J. H. Emertou. It differs from 

 its European congener by the pedipalps being twice as long, while the tarsal joints of the three 

 hinder pairs of feet are much fewer in number, there being twenty-four well-marked ones on the 

 second pair of legs of If. dentipalpe, while the fifth joint of the leg (including the coxa) is subdi- 

 vided in dentipalpe into thirteen subjoints, these divisions in N'. troglodytes not being well marked. 



From the European N. bimaculatum (Fabr.), French specimens of which have been kindly 

 loaned by Mr. J. EL Emerton, our species differs iu the body being much narrower and slenderer, 

 while the maxillae and legs are much longer, the tarsi especially being much slenderer and the 

 joints very much less distinct. The back of If. bimaculatum is not tuberculated. 



The European If. dentipalpe lives in moss in woods, while A r . lugubre (Muller=iV. bimaculatum 

 Fabr.) is, according to Simon, common in moss and detritus, etc. The effects of a cave life on the 

 American species is seen in the very long palpi and legs and the indistinct sub-joints. 



Nemastoma inops Pack. Plate XIV, figs. 4, 4o-4e'. 



Nemastoma inops Pack., Amer. Naturalist, xviii, 203, February, 1884. 



Body of the usual form, in general like the European If. lugubre and our N. troglodytes, the 

 abdominal segments being nearly the same, but as the specimen is immature it is not chitinized; 



Fig. 15. — Nemastoma troglodytes. 

 (Enlarged. Emerton, del.) 



