THE OLIGOCHiETA TERRICOL^. PART I. 185 



segments XII and XIII. In the 2 remaining, fully mature 

 examples, the clitellum was rather longer than those 2 seg- 

 ments taken together. 



The dorsal pores certainly commence between segments XII/ 

 XIII. Earlier than this, I have not been able to recognize 

 them. They are obvious, as already mentioned, upon the cli- 

 tellum, and they extend to the very end of the body. I found 

 a perfectly well-marked dorsal pore between the preanal and 

 the perianal segments. Genital paiyillse are entirely wanting 

 in this species. 



Of the intersegmental septa it may be said that none of them 

 is very greatly thickened, yet some of the anterior septa are 

 distinctly thicker than others. The first recognizable and defi- 

 nite septum divides segments IV/V; this and the two following 

 septa are slightly thickened as compared with those in the poste- 

 rior region of the body. Between VII/VIII is a delicate, thin 

 septum contrasting with the foregoing. The Vlllth, IXth, and 

 Xth segments, in which of course lies the gizzard, are not sepa- 

 rated by septa at all,^ and the intersegmental boundaries are the 

 only limits of the segments in question in the gizzard region. 

 The septa dividing X/XI and the 3 following segments are some- 

 what thickened and equally so. Thereafter, the septa are delicate 

 to the end of the body. 



Certain features in the alimentary canal of this genus serve 

 to discriminate species from species. Therefore, I shall direct 

 attention to the general anatomy of the gut, though several of 

 the facts to which I shall refer have not yet been made use of 

 in definitions of species and are not yet known to vary. The 

 gizzard belongs presumably to segment VIII as in other members 

 of the genus; it is elongated and barrel-shaped, being longer 

 than broad. After the gizzard, and extending to the end of the 

 Xlllth segment, is a very vascular section of the oesophagus 

 which doubtless represents potentially the calciferous glands of 

 other earthworms in which these glands occur; they appear to 

 be always absent in the genus Pheretima. In XIV, XV, and 

 XVI, the oesophagus is narrower and not vascular or, at least, 

 not so markedly vascular as anteriorly. The wide intestine 

 begins in the XVIIth segment. Some discrepancy will be noticed 

 between this enumeration and that of other writers. The large 

 intestine has been variously described as commencing in the 

 XVth or XVIth segment. It may be that this statement is 



* It is probable, of course, that the wall of the testicular sacs represent 

 a portion of the otherwise missing septum IX/X. 



