330 BNTOZOA. 



at the borders of which the ordinary circular strias of the integument terminate ; tail of 

 the male curved, and emitting at the extremity a short, tubular penis-sheath, armed with 

 minute retroverted spines ; tail of the female straight and bluntly pointed ; eggs ■^" to 

 ^ly" in their longest diameter. 



Few of the entozoa have excited more interest than this species, 

 partly owing to the angry discussion which its discovery inau- 

 gurated, and partly on account of its singular and elegant whip- 

 like appearance. The original name of Trichuris, given to it by 

 Buttner, could not, of course, be allowed to stand when it became 

 evident that the so-called tail was in reality the head and neck. 

 The Trichocephalus is generally thought to be scarce in England — 

 a persuasion which has possibly arisen from the neghgence of 

 pathologists, whose arduous duties, connected with the superin- 

 tendence of post-mortem examinations, have perhaps left them httle 

 time for these inquiries. On the other side of the Channel, this 

 worm is so abundant in some locaKties that M. Davaine calculates 

 that not less than one-half of the inhabitants of Paris are infested 

 by it. According to Dujardin, it can be scarcely less abundant in 

 IS^orthern France, for M. Duval, the distinguished director of the 

 Eennes School of Medicine, supphed that helminthologist with 

 numerous specimens, apparently, on many different occasions. Of 

 late, I have gradually become more persuaded that this parasite is 

 really rather a rarity this side the Channel, especially since my 

 friend Mr. Noel has assiduously striven to detect the presence of 

 these worms, in the post-mortem room of the Middlesex Hospital, 

 for nearly a year past without any other than a negative result. 

 Until lately, the only specimens, five or six in number, which I 

 have had an opportunity of examining in the fresh state, I owed 

 to the liberality of Dr. Haldane, who found a considerable number, 

 in one case, whilst acting as pathologist at the Eoyal Infirmary of 

 Edinburgh.* 



Structure and Development. — The general organization of 



* Since the above was written, and very recently (June, 1864), Mr. Noel has suc- 

 ceeded in finding IMchocephalus dispar in two separate subjects. — T. S. C. 



