ISOFODS OK NORTH AMERICA. 439 



longer. Last scoincnt of tlai;vllimi with u s})ino inoi-e tluiii twice. 

 liMiuth of seo-inent, hesido wliicli tliciH^ i.s an olfai-torv ciul) two-thirds 

 as loiio" anothei' soiiiowiiat shoitci- olfactoiv cliil) on penultimate 

 scomcnt. Last soomoiit of tiic basal portion of the inner antenna^ 

 l)ro\ ided witii thi'ee spines, as in (\ !<ty(jl((. Outer antennjv prol)al)ly 

 as long as body. Basal portion of live segments, the tirst three short 

 and thick, the fourtli and tiftli much longer and more slender. The 

 tlagcllum consists of at least forty segments. Mouth parts essentially 

 as those of C. siij(jl(i. Legs long and slendei", tirst pair subchelate, 

 remaining ones with a weak claw. Inferior margin of the body seg- 

 ments beset with short spines. Size, very small, probat)ly not over 

 o nun. in length. Coloi', white. 



■ ' Ilah'dat. — Subt(>rraiiean sti'eam near San Marcos, Texas. Collected 

 bv Dr. C. H. Eigenniann. from th(^ l'. S. Fish Connnission well. 



'"The above description is from a fragment. The telson and caudal 

 appendages were gone, also part of the outei- antemne. The writer 

 hopes soon to receive the material which will enable him to till out the 

 gaps in the above diagnosis. 



"In honor of Dr. 11. M. Smith, in charge of scientific inquiry of 

 the r. S. Fish Conunission.'' — C. J. Ulrich." 



Family XVI. STENETRIID.E.'' 



Eyes present, large, sub-dorsal. Body depressed, elongate. 



First pair of antenna^ with flagellum composed of several articles. 

 Second pair of antemue with multi-articulate tlagellum. 



Mandibles with palp. 



Lateral margins of thorax t)iit little produced, not laciniate. First 

 pair of legs in both sexes subcheliform; following ])airs amt)ulatory, 

 with dactylus bi-unguiculate. 



Scale present outside of third joint of peduncle of second antenna*. 



First pair of pleopoda in female with appendages fused to form a 

 small operculum. Second pair wanting. Third jjair with the outer 

 branches large, and forming, with the corresponding lamella of the 

 opposite side, a sort of o])erculum. Fourth pair witli two branches. 

 Fifth pair consisting of a single branch. 



First pair of pleopoda in male small, with the peduncles fused; 

 branches single. Second pair situated below and not coupled with the 

 tirst pair; branches attached to the distal part of the inner margin of 

 the peduncle; inner branch geniculate, with distal joint narrow and 

 without cavity in its obtuse end; outer branch very short, much 

 shorter than inner one, and unjointed. Third, fourth, and tifth pairs 

 similar to those of female. 



« Trans. Amer. Microscopical Soc, 24th annual meeting, 1902, p. 93. 

 ^' See Hansen for characters of family, T'roc. Zool. Soc. London, 1!)05, IT, T*t. '1, 

 p. 315. 



