PARASITIC ROUNDWORMS 523 



14 (9) Male with bell-shaped bursa encircling posterior end; no supporting 



ribs in bursa. No buccal capsule. 



Family DIOCTOPHYMIDAE Railliet 1915. 



Mouth surrounded by one or two circles of papillae, 6, 12, or 18 in number. Esophagus 

 very long, without bulb. One ovary; vagina very long. Vulva near anterior end; anus 

 terminal in female. One long spicule. Eggs with very thick pitted shells. Large worms, 

 in some genera armed with spines near anterior end. 



Only genus parasitic in North American aquatic hosts. 



Dioctophyme Collet-Meygret 1802. 



Anterior end unarmed; mouth surrounded by six papillae. 



Only species known Dioctophyme renale (Goese) 1782. 



Color blood red; six circumoral papillae and 150 along lateral lines. 

 Male up to 40 cm. long, 4 to G mm. broad. Anus terminal, surrounded 

 by circular bursa without ribs. Spicule 5 to 6 mm. long. Female up 

 to i m. long, and 12 mm. broad. Anus crescentic, terminal. Sex pore 

 only 50 to 70 mm. from anterior tip. Uterus single. Eggs oval; shell 

 brown, very thick, deeply pitted except at poles. 



In pelvis of kidney of seal, otter, dog, wolf, etc. Rare in man. 

 Reported from mink and dog in Pennsylvania by Leidy. Found in 

 dogs at Chicago, Illinois. Intermediate host probably a fish. 



The giant among nematodes; a dangerous and little-known parasite. 

 Another form which may belong here was collected in Florida by 

 Wyman from the water-turkey or snake-bird and described as "nearly 

 if not identical with Eustrongylus papillosus Diesing in Plotus anhinga 

 FIG. 8x6. Dioctophyme from Brazil " The species last men tioned was included in the genus 

 fp v f TAftPrRilPv Hystrichis by Molin, but as the identification of Wyman was not final 

 and Chandfer.) it is impossible to enter Hystrichis papillosus definitely among North 



American species. 



15 (8) Bursa absent or weakly developed in male. True buccal capsule 



wanting 16 



Compare the discussion under 9 (14) in this key. The caudal alae, often but incorrectly 

 called a bursa, when present consist of long, narrow wings not projecting conspicuously from 

 the body but parallel to it and not supported by radiating ribs, but having at most a series 

 of canals at right angles to the body. 



16 (51) Very long, slender forms, with or without lips 17 



17 (26) Esophagus slender, simple, no bulb. 



Superfamily FILARIOIDEA Weinland 1858 . . 18 



The anterior end is usually plain and no lips are present though in some cases a few minute 

 oral papillae can be recognized. The esophagus has only a single region. The posterior end 

 of the male is rolled into a close spiral of two or more coils. The vulva lies far anteriad and 

 the forms are usually ovoviviparous. The group as now conceived is much more sharply lim- 

 ited than formerly. 



1 8 (19) Anus wanting in adult; vulva lacking in adult female., 



Family DRACUNCULIDAE Leiper 1912. 



The famous guinea-worm of man known since ancient times belongs in this group. After 

 impregnation the sexual pore disappears and no trace of it has been found in the adult. The 

 females grow to a relatively enormous size coincident with the development of great numbers 

 of minute embryos which fill the uterus. The larvae develop in aquatic organisms, prob- 

 ably Copepoda, Ostracoda, etc. 



Only North American genus Ichthyonema Diesing 1861. 



Mouth surrounded by four low papillae. No buccal cavity. Esophagus funnel-shaped at 

 origin. One esophageal gland with large nucleus. Polymyarian. Uterus broad, traversing 

 entire body, with short ovary at each end. Embryos develop in uterus. No anus, vulva, or 



