ASCAKIS LUMBRICOIDES 71 



America. The species of the genus Oesophagostomum are 

 peculiar in that the larvae are often found in tumorous 

 nodules of the intestinal wall. The distribution and pre- 

 valence of these forms in man is still insufficiently known. 



J. Family Ascaridae 



Large thick nematodes; mouth with three lips, one dorsal 

 and two lateral; esophagus with a bulb; male with two 

 spicules; female with two ovaries; development direct. 



A scans lumbricoides. Very large worms; male measures 

 15 to 25 cm. in length and about 3 mm. in diameter; posterior 

 end is conical and hooked ventrally; spicules measure 2 mm. 

 in length are curved and somewhat broadened at their free 

 end; female measures 20 to 40 cm. in length and about 

 5 mm. in diameter; posterior extremity conical and straight; 

 vulva at junction of anterior and middle thirds of the body; 

 development of larvae in egg requires considerable time; 

 infection direct without intermediate host but with wander- 

 ing of larvae through the tissues especially lungs before 

 they settle in intestine; may produce intestinal disturbances; 

 wandering of larvae probably produce pulmonary disturb- 

 ances especially in children; habitat small intestine; cosmo- 

 politan in distribution. 



Two doubtful species, Ascaris texana and Ascaris maritima 

 have been described from man. A rare form Lagochilascaris 

 minor has been described from Trinidad, which is easily 

 distinguished from Ascaris lumbricoides by the presence 

 along the lateral lines of cuticular wings extending the 

 whole length of the body. Toxascaris limbata from the 

 dog and Belascaris cati from the cat have been reported a 

 few times from man. 



