INTESTINAL WORMS. 165 



body is cylindrical. The sexes are distinct. They are named Thread- 

 worms or Round-worms (Nemato'idea, from vrjp.a, a thread, and eiSos). 

 CUVIER makes a distinct order of this division, that of Intestinaux 

 cavitaires / all the remaining entozoa he unites in a second order 

 under the name of Intestinaux parenchymateux. OWEN has denoted 

 these two principal divisions of CUVIER by the names Sterelmintha 

 and Ccelelmintha 1 . In our compressed description of the structure 

 of the intestinal worms we shall avail ourselves of the names 

 which we have explained. 



In the cystic worms, the tape and thorn-headed worms, there 

 is neither mouth nor intestinal canal; the nutriment is introduced 

 by absorption of the skin. In the thorn-headed worms two parts 

 are met with by the side of the sheath of the proboscis, usually of 

 a flattened form, and very small anteriorly. These parts, called 

 Lemnisci, are, according to EUDOLPHI, subservient to nutrition. 

 They contain, according to the description of VON SIEBOLD, a finely 

 granular parenchyma, and are very vascular. 



In the suctorial worms the intestinal canal commences with 

 an oesophagus, more or less long, which, at its fore part (pharynx] 

 is surrounded by muscular walls. In those that have a sucker at 

 the anterior extremity of the body, the oral aperture is situated at 

 its bottom. The intestinal canal divides, below the oesophagus, into 

 two branches, which have csecal terminations backwards. In many 

 species these branches do not subdivide 2 ; frequently they expand at 

 their termination. In other species these principal branches give off 

 other branches. This is especially the case in the Liver-fluke of 

 sheep (Distoma hepaticum), where the branches divide to such a de- 

 gree that the whole canal has an arborescent appearance. The oral 

 aperture performs also the office of anus / at least the Distomes, 

 which are taken alive from the liver, and exposed to air or placed 

 in water, reject by the mouth, entirely or in part, the brown fluid 

 with which the intestinal canal was filled 3 . The genus Pentastoma 

 or Linguatula, differs from all the other suctorial worms in the 



1 TODD'S Cyclopedia n. p. in. 



2 As in Distoma perlatum NORDMANN, I. cit. Tab. IX., Distoma rosaceum, ib. Tab. 

 VIII., Diplostomata found in the vitreous humour of the eye of the Perch, ib. 

 Tab. n. in., and in many others. See also MAIJER Beitrage zur Anatomic der Entozoen. 

 Bonn, 1841, 4to. 



3 Comp. E. MEHLIS Observationes anatomicce de Distomate hepatico et lanceolate. 



