1890.] WORMS OF THE GENUS PERICH^TA. 53 



Old and New World, while Eudrilus has been recorded from South 

 America and the West Indies and from New Caledonia, and it also 

 occurs in New Zealand. 



I take this opportunity to put together a few notes upon other 

 species of Perichceta. 



Proposed Subdivisions of the Genus Perichseta, Schmarda. 



The genus was instituted by Schmarda (20), who, however, only 

 directed attention to the numerous setae forming a row round the 

 middle of each segment, and to the form of these setae. Vaillant 

 (22) subsequently described the internal anatomy of Perichceta, and 

 pointed out the important differences which distinguish the type 

 from Lumbricus. In the next year Eaird (1) called attention to the 

 identity of this genus with Megascolex, which was described by 

 Templetou (21) twenty years before the publication of Schmarda's 

 work. Tlie reason which, apparently, caused tliese two genera to be 

 regarded as distinct was a misunderstanding of Templeton's original 

 description. I have directed attention myself (2) to the fact that 

 both Schmarda and Vaillant misquoted Templeton's original descrip- 

 tion, making him responsible for the statement that setse are only 

 present on the dorsal surface of the body of Megascolex ; Templeton 

 himself defined the species as having " each ring in the middle of its 

 length dilated into a ridge, which carries on it, except in the mesial 

 line of the back, minute conical mamillse, 100 in number, each sur- 

 •iiounted with a minute bristle." These inaccuracies on the part of 

 Schmarda and of Vaillant have been also pointed out by Horst in a 

 paper published (15) about the same time as my own. 



Perrier, in his most important paper (18) upon the anatomy 

 of Earthworms, retains, in spite of Baird, Schmarda's name of 

 Perichceta; but the value of his opinion in the matter is greatly 

 discounted by the fact that, like his predecessors, he entirely mis- 

 understood and misquoted Templeton's description of Megascolex 

 cceruleus, probably taking his information from Schmarda, Vaillant, 

 or Grube. 



The synonymy of the genus was, I regret to say, somewhat con- 

 fused by my own paper (2) upon a large Ceylon worm, which I 

 described under the name of " Pleuroch(eta moseleyi." I was led 

 to describe this form, wliich I afterwards (4) recognized as iden- 

 tical with Templeton's Megascolex cceruleus, as belonging to a 

 new genus, on account of the inaccuracy and incompleteness of 

 Templeton's description. In a subsequent paper (8), dealing partly 

 with the nomenclature of the genus, I proposed to retain the name 

 Megascolex for "those worms which are characterized by (I) the 

 presence of a continuous ring of setae upon the segments of the body, 



(2) the possession of a clitellum occupying segments 14-10 inclusive, 



(3) the position of the two male generative apertures upon the 



eighteenth segment behind the clitellum ; while the name 



Perichceta might be applied to certain other forms which present a 

 fundamental resemblance to the above-mentioned groups, but differ 



