160 



BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



ARACHNTDA. 



Is emastoma troglodytes^ n. sp., (Fig. 5, enlarged*), 10 ? . — Body rather 

 long and slender comj)ared with the European N. dentipaJpis Koch, 

 the latter being short and ovate, while our spe- 

 cies is contracted at the base of the abdomen. 

 The eye-tubercle is rather large and prominent ; 

 the eyes themselves well developed, black in re- 

 cently-moulted specimens, but in others scarcely 

 distinguishable from the dark-brown, finely- 

 shagreeued tegument. Behind the eyes the body 

 contracts dorsally as well as laterally. On the 

 front edge of the cephalothorax is an acute 

 median spine. The six basal abdominal joints are 

 coalesced, forming a single piece, segments 3-6 

 being indicated by a pair of somewhat trans- 

 verse, high, well-marked tubercles (not forming 

 true spines as in JS^. dentipalpis). The four ter- 

 minal segments are free ; the terminal one sub- 

 triangular, one-fourth shorter than wide. Be- 

 neath are seven well-marked sterna, with lunate, 

 dark spiracles on the sternum of the second seg- 

 ment. 



Mandibles hairy, with the basal 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. Maxillary 

 palpi very long and slender, hairy, nearly 

 twice as long as the body, while in the Euro- 

 pean dentipaJpis they are scarcely half as long in 

 proportion; 6-jointed (m dentipalpis 5-jointed), the basal joint subtriangu- 

 iar in outline, 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 X. dentipalpis, with all the 

 coxte 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 4-7, together a little longer than the terminal one ; a single, 

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

 body; tarsi very long and sinuous like a whip-lash, 16-jointed, the sec- 



* The drawings of this and Figs. 6 and 8 have been made, under my direction, by Mr. 

 J. S. Kingsley, Salem, Mass. 



Fig. 5. — Neinastoma troglodytes. 

 Pack., n. sp. (enlarged). 



