NEMATODA 243 



one on either side of the head ('Die Mensch. Par./ Bd. ii, 

 s. 877). 



This entozoon was discovered by Dr Pfaff at Jacobshavn, near 

 Godhavn, West Greenland, in April, 1865. Two years later 

 he sent the specimen to Krabbe, who afterwards transmitted it 

 to Leuckart. In the original communication addressed to the 

 Copenhagen helminthologist, Dr Pfaff states that he procured 

 the worm from amongst matters vomited by a child, and he 

 incidentally observes that he had hitherto encountered only 

 Sothriocephalus cordatus and Oxyuris vermicularis amongst 

 Greenlanders. As to the source of infection, Prof. Leuckart 

 not unnaturally refers to the similar conditions of existence 

 shared by the human and carnivorous inhabitants of that 

 country. It is well known that bears, polar-bears, seals, and 

 walruses are largely infested by nematodes (Asc. transfuga, 

 A. osculata, Ophiostoma dispar, &c.), but these various species 

 are quite distinct from Dr PfafP s little " spulwurm." 



Ascaris lumbricoides, Linneus. This common parasite was 

 for a long while regarded as identical with the great lumbri- 

 coid of the horse, but the question has been finally settled by 

 Schneider, who has shown that the human worm, although 

 identical with Dujardin's Ascaris suilla of the hog, is never- 

 theless quite distinct from the Ascaris megalocephala of solipeds. 

 The large lumbricoid occasionally found in the ox belongs to 

 the human worm. Our large human helminth resembles the 

 common earth-worm in general appearance only. The males 

 usually measure from four to six inches in length, and the 

 females from ten to fourteen inches. Some have been reported 

 up to seventeen or eighteen inches in length. The body is 

 smooth, fusiform, and elastic, and marked by numerous fine 

 transverse rings. It is attenuated towards either extremity, the 

 anterior end terminating in a prominently three-lobed mouth 

 The tail is bluntly pointed. The female is much shorter than 

 the male, having a diameter of nearly a quarter of an inch. The 

 male is supplied with a double spiculum, its tail being always 

 more or less curved towards the central surface. The female 

 reproductive orifice is situated above the centre of the body. 

 According to Schneider, the tail supports from 138 to 150 

 caudal papillae, that is, from 69 to 75 on either side of the 

 median line. Below the anus the papillae are regularly 

 arranged in pairs, .seven in number, the two uppermost pairs 

 being double. 



