The Graspedosomatidse of North America. 59 



of eyes, with their accompanying nerves and ganglia having dis- 

 appeared. A compensating h3'pertrophy of the olfactory organs 

 is noted. 



ZYGONOPLTS Eyder. 1881. 



Proc. U. S. Nat. MuseiTm, Vol. Ill, p. 524. 



Zygonopus, Packard: Proc. Amer. Philos. Soc. XXI, p. 194 (1833). 



Eyes "wanting. 



Antennae rather stout, subclavate, fifth joint longest and thickest. 



Mandibles with eight pectinate lamellse. 



Promentnm not distinct.* 



Segments with moderate, shoulder-like carinse, the surface delicately areo- 

 late, appearing smooth ; setigerous tubercles prominent, setae long. 



Male legs with last joint not hispid. 



Cosse of second male legs Avith conic processes; legs without the cushion- 

 like processes present in Conotyla. 



Sixth legs of male much crassate, especially the fourth joint. 



Male genitalia simple, consisting of a deeply bifid lamina and two laciniate 

 processes. 



Ninth legs of male two-jointed, the distal stout, obclavate, with a small 

 chitinous knob on its outer face. 



Segments of adult 30. 



Distrihution : Luray Cave, Virginia. 



On account of the small size of the animal and special difficulty 

 of manipulation, we were not able to satisfy ourselves whether 

 the coxae of the tenth and eleventh pairs of legs of the male are 

 perforate. 



In many of its characters this genus shows such evident and 

 close relationship with Trichopetalum that we have sometimes 

 doubted its validity. On the other hand the characters by which 

 it is distinct from that genus (e. g., want of ej'es, swollen sixth 

 legs of males, conic process of second legs, and 30 segments) are 

 so numerous that there seems ample ground for retaining it. 



The similarity to Scoterpes is probabl}^ even more striking, since 

 both are cave animals, lack ej^es, and are more or less soft-bodied. 

 We have not had the opportunity of making a study of Scoterpes, 

 but retain both genera, believing that the differences in the sixth 

 and ninth male legs are sufficiently important to warrant such a 

 course, and that these are indicative of the probable existence of 

 still other differential characters. 



* The microscopic preparation was not sufficiently successful to make this 

 certain. 



