54 MR. F. £. BEDDARD ON [Feb. 4, 



in one or both of the following characters: — (1) in the ring of setae 

 upon each segment being discontinuous at one or more points ; (2) 

 in the clitellum occupying more or fewer segments of the body than 

 three." 



Rosa has lately pointed out (24) that my distinctions are valid, 

 but that the names should be reversed. I am now quite prepared 

 to agree with him ; at the time when I wrote I was inclined to con- 

 sider that Templeton's Meyascolex was identical with Perichceta, 

 even to the extent of having a continuous circle of setae in each seg- 

 ment, inasmuch as Baird (1), who had examined the type in the 

 British Museum, stated that he could find no difference between it 

 and Periclueta. Taking for granted the accuracy of Baird's obser- 

 vations, it appeared to me necessary to use the name Megascolex for 

 the worms which Schmarda termed Fericheeta ; strictly speaking I 

 should have allowed the name Perichceta to drop, but it was pro- 

 posed to retain it for perichcetous worms with a dorsal and ventral 

 interrupted line &c. 



When I discovered (4) that my Pleurochceta was identical with 

 Templeton's Megascolex cceruleus, it seemed necessary to restrict 

 the generic name to that form, and to group all the other known 

 perichtetous forms under the genus Perichceta; it will be seen that 

 the definition of Perichceta appended to that paper includes such 

 forms as P. armata. though I omitted to state in so many words 

 that it was proposed to drop the generic distinction between Mega- 

 scolex affinis and Perichceta armata, since the differences between 

 Megascolex cceruleus and any other perichsetous worm are rather 

 more important than those which differentiate the latter species 

 among themselves. 



Rosa (24) has, as already stated, proposed to divide Megascolex 

 from Perichceta by the distribution of the seta? and the presence or 

 absence of intestinal caeca ; the genera are thus defined by him : — 



Megascolex. Line of setae interrupted ; no intestinal caeca. 

 Fericheeta. Line of setse continuous ; intestinal caeca present. 



Fletcher (17, in.) has proposed a similar division, but also (17, ii.) 

 has pointed out that in the typical PeiHchceta, with continuous row 

 of setae and caeca, the gizzard is situated further back than in Mega- 

 scolex and occupies two segments, the mesentery between them 

 having vanished'. 



Tliis distinction, although it applies to so large a number of 

 species, falls to the ground before the Indian species descril)ed bv 

 Prof. Bourne^; Perichceta liulikalensis (Bourne, 11. p. (itiy) has 

 dorsal and ventral gaps, but possesses intestinal caeca in the usual 

 position. 



^ I had previously directed (6) attention to this difference between certain 

 species of Perichata, though mistaken in supposing that in P. newconthci the 

 gizzard occupied thi-ee segments ; I ha\e since convinced mjself the giziard is 

 really in segment (i ; in any case this species does not fit in very accurately witli 

 the jiroposed subdivision of Fericheeta. 



- This paper was overlooked by Rosa, as he nipiitlous in a poslsci-ipt (24- 

 p. 11). 



