DIAGNOSIS OF ASCAROPHIS HELIX 



393 



twenty times as long as the body of the nema is wide, and at its greatest 



width about one-third as wide as the nema. Sperms have not been seen, 



nor has the extent and nature of the oviduct been observed. The two 



uteri are filled with six to eight hundred ellipsoidal eggs about one-third as 



long as the body is wide and averaging 40 X 24 microns. For a short dis- 



tance near their equator the eggs are practically cylindrical. The shells 



are thick a little over 2 microns and structureless looking; are of uniform 



thickness throughout; and, as seen in the uteri, are without any surface 



markings or appendages. No indications were seen of "two flagellae at one 



pole," as noted by van Beneden and Nicoll. It is possible that appendages 



might arise later, e.g., from some vaginal secretion coagulated during deposi- 



tion. The eggs, before deposition, contain fairly well developed larvae. 



There is a single ovijector of considerable length passing inward from the 



vulva; apparently the ovijector is several times as long as the body is wide, 



say at least three times. Its walls are thick and muscular; viewed in 



optical section it is nearly one-third as wide as the body, being somewhat 



flattened when collapsed, and so, in cross-section, a little more than half 



as wide as long. Its lining is thin 



and strongly refractive; the wall, 



when seen in optical section, is 



glassy internally and fibrous ex- 



ternally. The vulva is a transverse 



ellipsoidal affair near the middle 



of the body, about one-fifth as wide 



as the corresponding portion of the 



body and interrupting two to three 



of the spirals. It is about twice as 



wide as long, is distinctly marked, 



and presents a double refractive 



contour, especially posteriorly. 



The excretory pore is an opening 



of considerable size, taking up the 



space of about three annules of 



the cuticle. For a short distance 



the tube is strongly refractive, 



then suddenly becomes almost in- 



visible. In the specimen under 



examination it is impossible to follow it far enough to say whether in its 



course it becomes double and symmetrical or remains single and asymmetrical 



(Fig. 1, p ex.) 



Diagnosis: Ascarophis having a length of 13 mm.; striae helicoid, the 

 sub-cephalic ones very fine and not retrorse, the posterior ones very coarse 

 and compound, their maximum obliquity, behind the nerve-ring, 30; 

 the two labial projections broadly conoid; pharynx tubular, 1.1%; tail 

 convex, and rather symmetrically short-conoid, 0.2%; eggs without polar 

 filaments. 



Habitat: Gills of the fish, Dasyatis centrum, Sting-ray. G. A. MacCal- 

 lum, Woods Hole, Mass., August, 1927. Hitherto Ascarophis has been 

 found only in the intestinal canal of fishes. The plurality of helices has 

 probably evolved through anastomosis; this anastomosis, if increased in 

 extent and systematized as shown in the diagrams (Figs. 5, 6 and 7) could 

 give rise to helical striae. \ The anastomoses in A. helix, as far as seen, are 

 lateral. 



Mix ^^====^^ 



Fig. 8. Somewhat schematized drawing of a 

 cross-section of Ascarophis helix, taken not far 





