PACKARD ON A NEW CAVE FAUNA IN UTAH, 161 



ond joint half as long as the first. Third pair of legs of the same length 

 as the first pair ; tarsi 8 jointed, the two terminal joints subdivided into 

 two joints. Fourth pair nearly three times as long as the body 5 tarsi 

 8-joiuted, the two last sometimes subdivided into two subjoints (inter- 

 nodes). Length, 3 millimeters. 



Found under stones on the bottom of the cave, 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 JSfemastoma dentipalpis of Koch, a specimen of which has 

 been kindly loaned me for the purpose by Mr. J. H. Bmerton. It differs 

 from its European congener by the maxillary palpi 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 N. dentipalpis, while the fifth joint of the leg (including the 

 coxa) is subdivided in dentipalpis into thirteen subjoints, these divisions 

 in iV. troglodytes not being well marked. 



From the European N'. himaculatum (Fabr.), French specimens of 

 which have been kindly loaned by Mr. J. H. Emertou, our species differs 

 in 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 N. bimacidatum is not 

 tubercnlated. 



Judging by its shorter limbs, the better-marked tibial and tarsal 

 joints, and tlie dark integument, the European N. dentipalpis probably 

 lived under stones in the open air. The effects of a cave life on the 

 American species is seen in the very long palpi and legs and the indis- 

 tinct subjoints. 



The genus Nemastoma of Koch is regarded by Thorell as the type 

 of a distinct family, Nemastomidce. It differs from the Opilionidcv in 

 the more distinct abdominal segments and unarmed maxillary j)alpi, 

 and for this reason I do not see that the genus differs sufiiciently from 

 Fhalangiiim, the type of the latter family, to constitute a family-type 

 but should advocate regarding it as the type of a subfamily of Ojnli- 

 onida', for which the name Nemastomince Thorell might be used, the 

 genuine Phalangidce (Phalangides, Leach, 1812) being thrown into a 

 subfamily, which may be named Phalangince. 



MYRIOPODA. 



Polydesmus cavicola,u. s]). (Fig. G. — «., antenna; h, section of a segment ; 

 e, two segments, dorsal view ; d, two terminal segments, all enlarged). — 

 Body consisting of 19 segments exclusive of the head, long and unusually 

 narrow, more cylindrical than usual. Head rather large and full, much 

 broader than the body, the sides bulging out more than usual, the body 

 in transverse section being much more rounded than either in P. ser- 



11 BULL 



