1901.] AND ARBANGf?)MENT OF EARTHWORMS. 197 



annulation. The fourth and fifth segments are each divided into 

 two by a median furrow ; the sixth is trianuulate ; the fact that the 

 setas occur in the middle ring of this segment, and on the anterior 

 of the two which are biannulate, shows that it is the anterior 

 annuh;s which is further subdivided. The three following seg- 

 ments have each four annuli, the setse being implanted upon the 

 second ring. Segments s., si., xii. are again triannulate. After 

 the clitellum the segments are more or less distinctlj triannulate 

 for a considerable distance back. The above description is drawn 

 up from the specimen which I have regarded as the type ; but the 

 others show no differences save for incomplete additional furrows 

 upon some of the segments. 



The prostomium is broad, and does not at all impinge upon the 

 first segment of the body. But a pair of furrows upon the first 

 segment make with it a T-shaped piece. 



There are naturally 8 seke per segment, arranged in couples. 

 The two couples of each side are close to each other and are quite 

 ventral in position. The two setse of the ventral couples are 

 distinctly closer together than are those of the lateral couples. I 

 found the lateral as well as the ventral setse upon the clitellar 

 segments ; and setae do not appear to be wanting upon the second 

 segment of the body. It is not, however, easy to see them, since 

 this segment, like the first, is marked by a number of short longi- 

 tudinal furrows \ 



The clitellum. of this species of Tyjjhoeits, like that of others, 

 occupies segments xiii.-xvii. 



Dorsal pores are obvious after the clitellum, but seem to 

 commence anteriorly to that part of the body. 



As is the case with the majority of the already known species 

 of the genus TypJioeus, T. nicholsoni possesses genital papillce. 

 There is a pair of these papillae upon all of the three specimens in 

 my possession, which are of a rather peculiar form. The area 

 occupied by the papilla is, according to the state of contraction of 

 the body, circular or more elliptical, the long axis of the ellipse 

 being at right angles to the long axis of the body. A complete 

 furrow separates the two papillae from the surrounding integument, 

 and they are separated from each other by a furrow. Their general 

 appearance and relations can be gathered from an inspection of the 

 accompanying drawing (text-fig. 54), which illustrates the ventral 

 surface of this worm. The two papillae occupy nearly the entire 

 space between the ventral setae of segments xv. and xvi. Laterally 

 they extend for a very short way outside of the area thus defined. 

 Each papilla has a central circular patch of different appearance 

 from the peripheral part. 



The spermathecal pores lie between segments vii./viii., and are 

 very closely approximated ventrally ; their orifices correspond in 

 position to that of the innermost seta of the ventral couple. 



The male pores are extremely conspicuous. They lie upon the 



^ This may possibly account for my failure to find them in T. gammii. 



Proc. Zool. Soc— 1901, Vol. I. ]S"o. XIY. 14 



