50 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. XXXII. 



Length, 5 mm. 



Specimens from Mammoth Cave, Kentucky, and Orleans, Indiana, 

 In this species the telson has a slight emargination, a feature which 

 does not accord with the definition of this genus. The other charac- 

 ters of the species, however, are so much like those of the recognized 

 members of the genus Crcmgonyx that it seems best not to assign it to 

 a new genus. The specimens upon which this description is based 

 were sent to me from the United States National Museum under the 

 name Orangonyx vitreus Packard. The specimens agree in the main 

 with Packard's description of this .species; however, he has described 



Fi(_i. 13.— Crangonyx vitreus, male. Mammoth Cave, Kentucky. 



his specimens so imperfectly that I can not be certain that the speci- 

 mens which I have described as C. vitreus belong to the same species 

 as Packard's. I have followed Packard in quoting Stygohromus vitreus 

 Cope, as a synonym of Crangonyx vitreus but from Cope's ver}^ short 

 description of his specimens it is very doubtful if they belong to the 

 same species or even genus as Packard's Crangonyx vitreus. 



CRANGONYX TENUIS Smith. 

 Crangonyx tenuis Smith, Kept. U. S. Fish Com., 1872-73 (1874), p. 656. 



I have had no specimens of this species for examination, but quote 

 the original description: 



A slender, elongated species, with very low ejiimera, reseinblinu- more in 'orm the 

 species of Niphargm than the typical species of ( 'rangonyx. 



