CCELHELMINTHES 227 



Family Metastrongylidse, Leiper, 1908. 

 "Buccal capsule absent. Male with two equal spicules and female 

 with two ovaries. Eggs in varying stages of development when ovipos- 

 ited. Embryo not rhabditiform. Parasitic in the respiratory and cir- 

 culatory systems. 



Subfamily Metastrongylinse, Leiper, 1908. 

 Type-genus Metastrongylus, Molin, 1861. 

 "Body usually very long and slender. Mouth with two lips or with- 

 out Ups and surrounded with circumoral papillae. Esophagus slender, 

 without posterior bulb. Anus subterminal. Male with a single spicule 

 or with two unequal spicules. Tail provided with papillae, usually 

 curved spirally, and with bursal alse present or absent. Female larger 

 than male. Vulva present, or, less often, absent in gravid females; 

 when present, usually anterior to the middle of the body or near the 

 middle, rarely near posterior extremity. Oviparous, ovoviviparous, 

 or viviparous. Development in many cases, perhaps in all, requires 

 an intermediate host. ' 



Superfamily Filarioidea, Weinland, 1858. 

 "Body long and fiUform. Mouth without Hps. Male with two 

 spicules, usually quite dissimilar. Vulva near the anterior extremity of 

 the body. Adults subcutaneous, in blood, or on serous surfaces. 



Type-family Filariidae, Claus, 1885. 

 "Vulva anterior, near mouth. Spicules quite dissimilar. Inter- 

 mediate stages, so far as known, occur in blood-sucking arthropoda. 



Subfamily Filariinse, Stiles, 1907. 



Type-genus Filaria, Mueller, 1787. 



"Mouth with two lips; or without lips in forms where vulva is near 



posterior extremity of body. Male with posterior extremity of body 



commonly expanded and alate. Female with vulva usually in middle 



portion of body, exceptionally near posterior extremity. 



FamUy Spiruridse, OErly, 1885. 

 Type-genus Spirura, E. Blanchard, 1849. 

 "Body long and filiform. Anterior portion of body ornamented with 

 cuticular bosses. In the median lines, immediately behind the mouth, 

 are two semilunar depressions simulating suckers. The vulva is sit- 

 uated a short distance anterior of the anus. 



Subfamily Gongyloneminse, Hall, 1916. 

 Type-genus Gongylonema, Molin, 1857. 

 "Females with two uteri and with vulva in the middle portion of 

 the body, not close to anterior or posterior extremities. Pharynx with- 

 out cuticular rays or spirals. 



, Subfamily Spirurinse, RaUliet, 1915. 



Type-genus Spirura, E. Blanchard, 1849. 



"Mouth with two Hps leading into a pharynx which is strengthened 



