80 MR. H. CHARLTON BASTIAiN'S MONOGRAPH 



' Sj'stema,' under Elirenberg's genus Angmllula (which is characterized in such general 

 terms as to he perfectly capahle of including the most diverse types) he places several 

 species of minute Nematodes found in the intestines of insects, myriapods, and other 

 animals, which were, for the most part, named by their original discoverers either Asca- 

 rides or Oxyiirides. An examination of the extremely imperfect descriptions given by 

 him, as well as of the figures hj their original discoverers ', seem rather to confirm the 

 former position assigned to them ; and from a consideration of the facts before mentioned, 

 I certainly should not be disposed to place in the same genus parasitic and non-parasitic 

 forms without more distinct evidence of their identity in anatomical details than we at 

 present possess"-. 



Since the classification of the Nematoids generally is in such a confessedly unsatis- 

 factory condition, it is quite impossible to indicate the precise position or affinities of 

 these non-parasitic forms. It seems, however, most desirable to retain for this group 

 the family name of ANGUiLLULiD^i;, proposed by Gervais and Van Bcneden ^, which is 

 not only generally suitable, but is also recommended by the fact of the most familiar 

 and first-discovered species having still retained for them the generic name of An- 

 giiillula. 



In the description of species and genera, and the arrangement of the former into the 

 latter groups, an extreme amount of confusion prevails concerning almost all the forms 

 hitherto discovered. This seems to have arisen partly from the meagre descriptions and 

 indefinite figures given, and partly, with more accurate and precise observers such as 

 Eberth, from their not having definitely settled what should be looked upon as points of 

 generic importance. ' Some of this confusion I hoj)e to be able to clear up in the more 

 special portion of this memoir, and also to indicate, as far as my observation has ex- 

 tended, the value of difi'erent anatomical peculiarities as guides to classification. 



Having thus sketched the history of our knowledge concerning this group of animals, 

 I will now add a few details regarding their structure, habits, and mode of life. I shall 

 merely give a brief outline, however, of their anatomy, as I intend to make this the sub- 

 ject of another communication. 



The integument is mostly very transparent and hyaline in appearance, of a chitinous 

 composition, and presenting sometimes transverse lines or dots, at others longitudmal 

 markings ^, either alone or with transverse also ; whilst in the remainder the integu- 

 ment appears perfectly plain, with no striae of any kind. I have discovered numerous 

 fine capUlary canals through the integument, establishing a communication, apparently, 

 between the exterior element and the peculiar lateral and median lines of these animals. 

 These minute channels vary much in their number and arrangement in different 

 genera, and promise to throw considerable light upon the nature of the cu.rious lateral 



' For references, see Diesing's 'Syst. Helminth.' vol. ii. pp. I32-I3G. 



- Diesing's Anguillula macrura I have lately found in the intestmes of Blatta orientalis, and have ascertained that 

 it has no re-emblance to any of the free Nematodes at present known. Its aiiatomicnl characters are totally distinct 

 from those of AnyuiUula aceti ; and it seems best to place it in a distinct genus {Strepfostoma), as was done by Dr. 

 Leidy (Smithson. Cent. 18J3, v. p. 46, fab. 7. f. 6, 7). ^ Zoologie Medicare. 



■* These mus i.ot be confounded with the longituJ'nal muscular bundles seen through an unstriated hitrgument. 



