320 ANIMAL PARASITES. 



their allies. With regard, to the latter, however, I do not know 

 whether each of the two lobate penes forms a furrow, or whether 

 the two together only form a single furrow. From this it will 

 be seen that in general I adopt Creplin's opinion, according to 

 which the penis of the Nematoida acts in the same way as the 

 ovipositor of many female insects. At the same time the penes 

 appear of themselves to effect the dilatation of the vagina of the 

 female, at least in soft-walled worms ; the simple ones, which are 

 conically pointed in front, but widened above and behind, must 

 act in the same way as simple uterine specula ; the double ones 

 like Ricord's speculum, and the lobate ones like those furnished 

 with several arms, such as that of Segalas. Sometimes, however, this 

 action is effected by peculiar organs entering with the penis into the 

 vagina, which we must certainly distinguish from sucking sur- 

 faces and structures like sucking lobes, and which we shall meet 

 with and describe amongst the Tricocephali 1 and also in the 

 males of Oxyuris and Strongylus. 



After this general introduction, I turn at once to the conside- 

 ration of the particular species. 



I. Trichocephalus. Synon. Trichuris (Roederer) ; Ascaris 

 (Linne) ; Mastiff odes (Zeder). 



The name of Trichocephalus proposed by Goeze in 1782 has 

 since met with general acceptance, and Zeder's attempt in the 

 year 1803 to substitute that of Mastiff odes for it, must be 

 regarded as a complete failure. 



In Diesing's system, the Trichocephali are placed in the Sub- 

 classis I, Achcethelmintha ; Sectio II, Achath. elastica ; Ordo VI, 

 Nematoidea ; Subordo II, Proctucha (ano instructa) ; Tribus III, 

 Gamonematoidea (tractus cibarius proprius simplex liber; organa 

 genitalia segregata) ; Sectio II, Acrophalli (penis in exlremitate 

 caudali e bursa protractilis) ; Familia I, Trichotrachelidea (collum 

 longissimum capillare ; penis in vagina tubulosa) ; XL III Tricho- 

 cephalus. Dujardin treats of the Trichocephali in the first class, 

 Nematoidea, of which they form the sixth genus. The exact 

 systematic description to be given, with the assistance of Diesing's 

 and Dujardin's works, is as follows : 



Corpus longissimum, ex 2 partibus formatum, quarum anterior, 

 tenuior filiformis posterior crassa, organa sexualia continent. 



' The corresponding auxiliary organ in Trichocephalus dispar is precisely like a three- 

 armed uterine speculum. 



