210 ON AUSTRALIAN ENTOZOA, 



are without an anus. Genital organs ai-e situated upon separate 

 individuals. Copulatorj organs are sometimes present. 

 Genera : Mermls, Gordius. 



Order VI. Nematodes. 



The body is sack-like and cylindrical. The digestive canal 

 has a mouth and anus, and passes in a straight line through the 

 cavity of the body. The genital organs are situated upon 

 separate individuals. Copulatory organs are present. 



Genera : Sphaerularia, Trichosoma, Trichocephalus, Filaria, 

 Anguillula, Physalo'ptera, Liorhynchus, Lecanoceplialus, Cheiracan- 

 thus, Onathosoma, Ancijr acanthus, Spirojptera, Hedruris, Strongy- 

 lus, Giicullanus, Oxyuris, Ascaris. 



I consider it also necessary (for the purpose of making those 

 interested better acquainted with what has been written on Aus- 

 tralian Entozoa) to give a complete list of the species already 

 described. This I propose to do in chronological order. 



The first Australian intestinal worm {Tcenia festiva) was 

 noticed by Rudolphi in the year 1819, in his " Entozoorum 



an unprejudiced eye, a fully developed Tmnia with its sexually matured 

 joints, must be convinced that it is no simple animal, but one composed of 

 many individuals." 



On page 44' : von Siebold remarks : — " In the Cestoidea the stock is the 

 posterior end of the scoliciform agamozooid (the head G.K.) In the alter- 

 nation of generations amongst the Cestoidea, there is this peculiarity that the 

 agamozooid preserves its efiBcacy and independence, whilst the agamozooids 

 of other animals which undergo alternation either die after producing- their 

 brood or pass into it. (Huxley doubts this : Gr.K.) We must consider the 

 head of every cestoid worm as the agamozooid still remaining and capable 

 of reproduction, and its neck as the equivalent of the posterior extremity of 

 the scolex. In all cestoids we see that fresh joints are continually being 

 developed at the posterior part of the neck which lengthens and becomes 

 covered with transverse folds. These folds are at first very close together, 

 but as the process of growth throws them backwards further and further from 

 their place of origin, they gradually change from indistinct wrinkles into 

 sharp transverse lines of demarcation, between which the substance of the 

 body dilates into a joint (individual), and assumes its specific shape. At a 

 later period the rudiments of the hermaphroditic sexual apparatus make 

 their appearance in the interior of the joints, and finallj' they separate 

 themselves from their younger fellows as independent individuals." 



