ABT. 17 A NEW NEMATODE — ROE S 



muscles; immediately posterior to it is a prominent cuticular ridge. 

 A small cuticular spine is located on the tip of the tail, forming a 

 mucronate tip. The anus is locat'ed about dO/j. ironi the tip of the 

 tail. The muscular ovejector, including the sphincter, is 350 to 450/x 

 long. The eggs are oval, thin shelled, 56 to 66/x long by about 35/li 

 wide, and embryonated within the uterus in our nuiterial. 



Host. — " Wild mouse." 



Location. — Small intestine. 



Locality. — New Jersey (Monmouth Junction), United States. 



Ti/i)e spec'nnot. — Cat. Xo. 25475, U. S. National Museum Helmin- 

 thological Collection. 



The outstanding characters in this genus and species in comparison 

 with other forms in the subfamily Heligmosominae or with stron- 

 gyles in general, is the absence of the dorsal ra}'. The branching of 

 an externo-dorsal, found in one specimen, and the enlarged base of 

 each externo-dorsal with the accompanying knob and depressions 

 found in all specimens, may or may not be vestigial remnants of the 

 dorsal ray. The alternative possibility, already noted, that the rays 

 present are dorsal rays, would suggest that the branching was a 

 remnant of a suppressed externo-dorsal ray. Subsequent develop- 

 ments in helminthology may afford definite evidence in support of 

 one of these alternatives. 



REFERENCES 



Hall, Maurice C. 



1916. — Nematode parasites of mammals of the orders Rodentia, Lago- 

 morpha, and Hyracoidea. Proe. U. S. Nat. Mus., vol. 50. pp. 1-258. 

 pi. 1, fig. 290. 

 YoRKE, Warrington ; and Maplestone. P. A. 



1926. — The Nematode parasites of vertebrates. With a foreword by C. W. 

 Stiles, xi-f-536 pp. 307 figs. London. 



EXPLANATION OF PLATE 



Sincosta aherrans, new species 

 an... anus ; e. d., externo-dorsal ray ; e. I., externo-lateral ray ; int., intestine ; 

 I. v., latero-ventral ray; m. I., medio-lateral ray; ovej. 1, 2, 3, ovejectors; p. I., 

 postero-lateral ray; sp., spicules; iit., uterus; I'ul., vulva; v. v., ventro-ventral 

 ray. 

 Fig. 1. Anterior end of male. 



2. Dorsal view of bursa. 



3. Spicules. 



4. Female showing characteristic tight spiral coil. 



5. Posterior end of female showing genital organs. 



6. Head, en face view. Enlarged. 



