PARASITIC ROUND WORMS 551 



35 (34) Proboscis with sixteen longitudinal rows of hooks. 



Arhythmorhynchus pumilirostris Van Cleave 1916. 



Female up to 30 mm. long, and 1.5 mm. broad. Proboscis 0.45 

 mm. long, 0.114 mm - wide at base, 0.095 mm. at tip, 0.18 mm. at 

 center. Embryos 65 to 89 fj. long, 18 p broad. Middle shell with 

 evagination at each pole. 



From bittern (Botaurus lentiginosus); Washington, D. C. 



FIG. 855. Arhythmorhynchus pumilirostris. Profile, anterior end of 

 body. X 95. (After Van Cleave.) 



36 (n) In anterior region of mature specimens prominent bulbous enlarge- 



ment, separated from body by slender cylindrical neck. 37 



The bulb is embedded in the intestinal wall or may even be in the body cavity when the 

 slender region traverses the wall connecting with the body of the parasite in the intestine. In 

 handling such material the proboscis may easily be partly or completely torn off, and the para- 

 site is then difficult to identify as the characteristic bulb at least is gone. 



37 (38) Bulb consists of the proboscis. Hooks on the anterior face of the 



bulb in radial lines. . . (Females of) Filicollis Liihe 1911. 



Representative North American species. 



Filicollis botulus Van Cleave 1916. 



In females thus far reported under this name for North America the bulb is wanting; it may 

 be present in older specimens and in fact is described in specimens recorded under the name 

 E. anatis which may belong here. 

 Compare number 22 in key. 



38 (37) Bulb consists of anterior part of neck only. Proboscis extends an- 



teriad from bulb. . . . Pomphorhynchus Monticelli 1905. 



Proboscis long, cylindrical, with many hooks. Neck very long, expanded in anterior region, 

 slender, cylindrical in posterior portion. In intestine of fishes; one of the commonest types 

 in European fresh-water hosts. Not infrequent in North American fresh-water fishes; species 

 not described. 



IMPORTANT REFERENCES ON NORTH AMERICAN PARASITIC 



ROUNDWORMS 



GENERAL WORKS 



See also list in Chapter XIII, page 452 



HAMANN, 0. 1891. Die Nemathelminthen. Heft i, 120 pp., 10 pi. 1895. 



Heft 2, 120 pp., ii pi. Jena. 

 LEUCKART, R. 1876. Die menschliche Parasiten. Vol. 2 [Nematoda, 



Acanthocephala]. 882 pp., 401 figs. Leipzig. 



