1904.] 



EATITHWORMS FROM NEW ZEALAND. 



253 



Diiaenslons. The largest specimen measures 70 x 4 mm,, and 

 consists of 75 segments ; the shortest mature individual measures 

 25 X 2 mm., and likewise consists of 75 segments ; and the same 

 number occurs in a worm of inteiinediate size. 



We have here an instance — unique, so far as I am aware — of 

 an earthworm increasing in lengtli without adding new segments 

 posteriorly. It is true that we do not know much on this subject ; 

 but the accepted view is that the number of segments is continu- 

 ally added to during growth. 



With regard to tliis. Beddard ('95, p. 2) states : — " There are 

 at present no exact data as to the constancy of tlie number of 

 segments among Earthworms. In all probability the number is 

 not absolutely fixed, but thei-e appears to be a mean for eacli 

 species round which there is a certain amount of variation." 



Text-fia-. 80. 



Tolcea maorica, similar view to tliat in text-tig. 62. (X 11.) 



Prostomiiim h epilobic ; without a transverse groove. 



Chcetal formula : — ah <cd<bc; be = 2 ah = aa; dd = 1 aa. 



Clitellum girdle-like, over the five segments 13 to 17. 



Genital pores, &c. (text-fig. 80). — On segment 18 is a transverse, 

 elliptical area, paler than its surroundings ; glandular centrally, 

 with a distinct margin surrounding it. It extends between points 

 a little outside a, on each side. This is a tuber culimi pttbertatk 

 (text-fig. 81, p. 254), and the male pore is situated on the thickened 

 margin, at each pole of the ellipse in line with a (which is absent 

 in this segment). There is a second tuhercidum pubertatis of the 

 •same shape, but of much smaller size, on the hinder border of 



