686 THE ANIMAL KINGDOM. 



development in the small intestine, enter the caecum, their head-quarters, 

 and are found throughout the whole large intestine ; Dochmius (Anchylo- 

 stotna] duodenalis, which inhabits the small intestine, and occurs in Europe, 

 Egypt, Comoro Is., Brazil, and Cayenne, and is the cause of a pernicious 

 anaemia ; Filaria Bancroft* s. F. sanguinis hominis, found in Australia, 

 China, India, Egypt, and Brazil, the sexual female of which inhabits the 

 lymphatic glands, is the cause of elephantiasis, lymph scrotum, &c. and 

 produces living embryoes circulating with the blood, giving rise to 

 chyluria and haematuria, and passing into a larval state within a mosquito ; 

 Dracunculus (Filaria) medinensis, the female only of which is known, 

 attains a length of 1-6 ft, lives encysted under the skin of the lower leg or 

 shoulder, produces living young which become larvae in a Cyclops, and is 

 distributed over certain districts of Asia (Arabia Petraea, Persian Gulf, 

 Caspian Sea, Ganges), of Africa (Upper Egypt, Abyssinia, Guinea), in 

 several W. Indian Is., and formerly in Brazil ; Trichina spiralis, rare in 

 England, found in the Pig as well as Man, the sexual worm of which 

 inhabits the intestines, is viviparous, and its progeny migrate through the 

 tissues and encyst in the muscles, causing what is known as Trichiniasis ; 

 Trichocephalus dispar, not uncommon in England and Ireland and the 

 Continent, infrequent in Scotland, which infests the caecum and upper part 

 of the colon, and the young of which appear to enter the body with water 

 or food; Rhabdonema strongyloides (=Leptodera s. Anguillula stercoralis 

 and intestinalis), which occurs in Cochin China and Europe, and has been 

 stated, but probably erroneously, to be the cause of a peculiar dysentery or 

 diarrhoea, at least in Europe, the disease being really due to associated 

 Dochmius (Anchylostomd) duodenalis 1 . 



The classification of the Nematoda is not easy. The class was divided by 

 Schneider into three sections : (i) Polymyarii, with many muscle-cells in each 

 quadrant of the body, e. g. Ascaris ; (2) Meromyarii, with the muscle-cells disposed 

 in eight rows, two rows in each quadrant, e. g. Oxyuris ; and (3) Holomyarii, with 

 the musculature of the body either undivided or divided only by the longitudinal 

 thickenings of the subcuticula, e. g. Trichina, Mermis. But this last section appears 

 to be founded on error. 



Orley has proposed to establish three sub-divisions : (i) Nematentozoa, (2) 

 Rhabditiformae, and (3) Anguillulidae, for the characters of which see his paper in 

 A. N. H. (5), ix. 1882, p. 301 et seqq. 



Claus distinguishes eight families : (i) Ascaridae (Ascaris, Heterakis, Oxyuris}; 

 (2) Strongylidae (Eustrongylus, Strongylus, Dochmius, Anchylostoma, Sclerostoma, 

 Syngamus, Pseudalius, Olullanus)-, (3) Trichotrachelidae (Trichocephalus, Trichosoma, 

 Trichina]-, (4) Filariidae (Filaria, Dracunculus, Ichthyonema]-, (5) Mermithidae 

 (Mermis, Sphaerularia] (6) Gordiidae, see infra ; (7) Anguillulidae, free-living in 

 fresh-water or earth or in plants (Tylenchus, Anguillula, Angiostomum, Leptodera, 

 Pelodera) ; (8) Enoplidae, free-living and mostly marine. 



1 Cf. A. N. 51, i, 1885, pp. ii-i2. 



