| OCR Text |
Show 1890.] WORMS OF THE GENUS PERICH.ETA. 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 Baird (1) called attention to the identity of this genus with Megascolex, which was described by Templeton (21) twenty years before the publication of Schmarda's work. The reason which, apparently, caused these 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 description, making him responsible for the statement that setae 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 surmounted 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 m y 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 misunderstood 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 confused by my own paper (2) upon a large Ceylon worm, which I described under the name of " Pleurochceta moseley.'." I was led to describe this form, which I afterwards (4) recognized as identical 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 (l)the presence of a continuous ring of setas 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 |
