NO. 1507. FRESH- WA TER A MPHIPODA— WECKEL. 5 3 



Length, 18 mm. 



Specimens examined from an artesian well San Marcos, Texas, the 

 type locality. 



OnuKjony,!' Ixurerml Ulrich is undonl)teclly the same species as Stij- 

 gcmectes fngt'llatas. The specific ditierences which Ulrich points out, 

 tog-ether with the rather small size of the single specimen which he 

 examined, indicate that he had an immature specimen. The only dif- 

 ferences which he gives are in the nnml)er of segments in the antennie 

 and the number of spines on the propodus, which in Crangonyx hcnv- 

 ersl! are less than in Sfygoticctes ffageUatdis. These are characters 

 which vaiy with age, there being fewer segments in the anteima^ and 

 fewer spines on the propodus in the immature forms. 



This is the type species of the genus Stygonecte.s to which it was 

 assigned by Prof. W. P. Hay. This genus closely resembles the genus 

 Crangonyx, but differs from it in having the last two segments of tho 

 urosome coalescent. 



Genus APOCRANGONYX Stebbing. 



APOCRANGONYX LUCIFUGUS (O. P. Hay). 



Crangonyx I uc if uguti O. P. Hay, Am. Nat., XV], 1882, p. 144. 

 Apocrangoni/.v lucifugtis Stebbing, Trans. Linn. Soc. London, 2d ser., VII, 

 1899, p. 422. 



This species is the type species of the genus Apncrangonyx to which 

 it has been assigned ])y Stel^bing. This genus diti'ers from Crangonyx., 

 in which the species was placed by Hay, in the rudimentary third 

 uropods which are without rami. 



I have had no specimens of this species for examination, l)ut quote 

 the original description: 



This is a small, rather elongated species that was obtained from a well in Abing- 

 don, Knox County, Illinois. As befits its subterranean mode of life, it is blind and 

 of a pale color. In length the largest specimens measure about (> mm. 



Male. — Antennuhe scarcely one-half as long as the body. The third segment of 

 the peduncle two-thirds as long as the second; this two-thirds the length of the first. 

 Flagellum consisting of about fourteen segments. The secondary flagellum very 

 short and with but two segments. Antennae short, only half as long as the antennula*. 

 Last two segments of its peduncle elongated. Flagellum consisting of but about five 

 segments, and shorter than the last two segments of the peduncle taken together. 



Second pair of legs stouter than the first. Propodite of first pair quadrate, with 

 nearly a right angle l)etween the palmar and posterior margins. Palmar margin on 

 each side of the cutting edge, with a row of about six notched and ciliated spines, 

 one or two of which at the posterior angle are larger than the others. The cutting 

 edge is entire. Dactylopodite as long as the palmar margin, and furnished along the 

 concave edge with a few hairs. 



Propodite of the second pair of legs ovate in outline, twice as long as broad. The 

 palmar margin curving gradually into the posterior margin. The cutting edge of the 

 palmar surface uneven, and having near the insertion of the dactyl a square projec- 

 tion. The palmar surface also armed with two rows of notched and <"iliated spines, 

 five in the inner row, seven in the outer. Dactyl stout and short. 



