^ I II. Monograjili Ion the Anguilluliclgey^r Free Nematoids, Marine, Land, and Jf'resh- 

 *^^'^ ' water; with Descriptions of 100 Neio Species. By H^ Charlton Bastian, 31. A., 

 M.S. Lond., F.L.S. ^^y 



(Plates IX.-XIII.) 



Read December 1st, 1864. 



Op the Helminths hitherto described, those belonging to the Nematode group far ex- 

 ceed in number of species the representatives of either the Trematode or the Cestode 

 orders, and, as far as our present knowledge extends, they have also a wider distribution 

 as parasites amongst the various members of the animal kingdom. Thus, commencing 

 with the AcalephcB, we find the so-called Nematoideum Cydippes taking up its residence 

 in the substance of the body of one of our smaller jelly-fish, and thence onwards through 

 higher and diverse types of animal life they are found, in more or less plurality, infesting 

 representatives of all the principal orders and classes, tUl we come to man himself, who 

 is the chosen habitat of no less than twelve species. Happily, however, whUst thus 

 numerous and widely diffused, their effects are less pernicious and more seldom fatal 

 than those resulting from the presence of individuals of the Trematode or Cestode types 

 in their various stages of development ^ 



As regards the actual number of parasitic jSTematoids at present known, it has been 

 computed by Dr. Cobbold, in his recent work on ' Entozoa,' that these do not amount to 

 more than about 550 distinct species ; and when I mention that within a space of fifteen 

 months I have obtained from a few limited regions no less than 100 new species of free 

 Nematoids, some idea may be formed of the numerical importance of this last group, 

 concerning which, tUl within quite a recent period, our knowledge has been so vague 

 and unsatisfactory. 



Borellus", more than two centuries ago, seems to have been the first to recognize and 

 describe a member of this family ; and we must look, therefore, upon the so-called "Vinegar 

 Eel," whose discovery he announced, as the first kno\^Ta rejiresentative of this group of 

 non-parasitic Nematoids to which I refer. The same animal was subsequently seen by 

 Power, Hooke, Leeuwenhoek, Baker, Spallanzani, and other pioneers of microscopical 

 research, who soon found a companion for it in its near aUy, the " Paste Eel." Then came 

 the discovery by Needham "% in 1743, of the wonderful Vibrio tritici and its young so 

 strangely tenacious of life ; and afterwards Otto Miiller"' was followed in his recognition of 



As exceptions to this general rule, three Nematoids may be cited which are undoubtedly most serious pests to the 

 human race, from the frequency of their occurrence and the serious diseases to which they give rise : these are tlie 

 Guinea Worm, which is so prevalent in the tropical parts of Asia and Africa ; Sclerostomum chwdenale, principally 

 met with in Egypt, and so common that Dr. Griesinger considers about one-fourth of the whole population suffer wore 

 or less from " Egyptian chlorosis" (a malady that is frequently fatal), due to the presence of these parasites in the 

 situation indicated by its name ; and, lastly. Trichina spiralis, which has attracted so much attention of late, owing 

 to the frequency of trichinosis, in various parts of Germany more especially. 



^ Obs. microscop. Centur. 7, 1656. ^ Micr. !)9, tab. v. 7. '' Animal. Infusoria. 4to. Hamb. 1786. 



VOL. XXV. L 



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