558 OLIGOCHAETA 



This species has been studied by myself only; it appears to be a rather rare 

 species, as in numerous consignments of worms from New Zealand I have only 

 come across two specimens. 



Genus PLAGIOCHAETA, BENHAM. 



DEFINITION. Setae, 50-54 per segment, arranged in couples. Nephridia paired ; 

 alternating in position. Penial setae present. 



This genus is only known by a single species. 



Plagiochaeta punctata, BENHAM. 

 P. punctata, BENHAM, Q. J. M. S., vol. xxxiii, 1893, p. 394. 



Definition. Length, 30 mm.; diameter, 5 mm.; number of segments, 89. Colour brown, with 

 white spots transversely disposed. Prostomium completely dividing buccal segment. 

 Cliiellum, XIV-XVIII, complete. Setae: 48 in, IF; 44 in III; 30 in II; behind, 

 50-54. Male pores bounded by a ridge on either side. No very thick septa ; those 

 of XIII/XVI slightly thicker than others. Gizzard rudimentary; calciferous glands 

 in XIV; intestine begins in XVI, spiral. Nephridia with caecum longer in case of dorsal 

 pairs, begin in II. Sperm-sacs in IX-XII. Spermathecae in VIII, IX, with a single 

 diverticulum. Hab. New Zealand. 



This species is copiously illustrated by BENHAM in his paper. The great breadth 

 of the body, as compared with its length, is one of the marked external characters ; 

 so, too, is the very peculiar colouring. The clitellum is of less diameter than the 

 parts of the body adjacent; this is a curious resemblance to many species of Perichaeta, 

 and unique among the Acanthodrilidae. 



Genus TBIGASTER, BENHAM. 



DEFINITION. Setae strictly paired. Clitellum extensive, XIII-XL. Three gizzards 

 in VII-IX ; calciferous glands absent. Nephridia difluse ; a mucous gland 

 present. Fenial setae absent. 



This genus only contains one species. 



