226 



PROF. W. B. BENHAM OX AQUATIC [NoV. 3, 



the nerve-cord. Each gknd consists of a bundle of long club- 

 shaped cells. 



Two pairs of globular spermathecse lie m the anterior moiety 

 of segments viii. and ix., and open laterally, at the anterior margin 

 of these segments. 



Dimensions. About 20 mm. x § mm. With about 60 segments. 



Locality. Lake Wakatipu, South Island of New Zealand ; from 

 a depth of 550 feet. 



DiPOROCH^TA AQUATicA, sp. n. (Plate XXVI. figs. 29-31.) 



Two individuals were obtained, of which one was entire and 

 well preserved ; the other, broken, soft, and almost useless for 

 study. The former was cut into sections. 



It is a short and relatively stout worm. 



The prostomium is small and prolobic. 



The chcetce are about 28 per segment, i. e. 14 on each side, and 

 the gaps aa — ah, zz — \^yz; thus the midventral "gap" is 

 practically absent. 



The clitellum is not fully developed in either individual ; it 

 appears to cover segments xiv., xv., xvi. and the dorsal region of 

 the 13th. 



The male pores, on the 18th segment, are distinctly visible under 

 a lens, but are not on papillse ; they are rather widely separated, so 

 as to lie, when seen from below, on the "edge" of the ventral 

 surface ; they are on a level with the chsetal gaps d/e. There are no 

 chsetse visible between these pores. 



The oviducal pores are paired, but close together on a pale oval 

 area, in line with chseta a. 



The spermathecal pores are not visible externally, but are on 

 the anterior margins of segments viii., ix. I did not note their 

 position relative to the chpetse. 



The nephridial pores are situated about halfway up the body- 

 waU. 



■ Internal Anatomy. 



There is no gizzard ; the oesophageal wall is vascular and 

 folded as it passes through segments x., xi., xii. It then diminishes 

 in diameter and becomes thin- walled in the next two segments, 

 dilating in the 15th, to attain the fuU diameter of the intestine 

 in the 16th segment. There is a minute typhlosole in the form 

 •of a small, low, rounded ridge, deeply separated from the rest 

 of the lining by a furrow on each side (PI. XXYI. fig. 29) ; 

 its epithelium differs from that of the general lining of the 

 intestine in that it consists only of ciliated columnar cells 

 (PI. XXVI. fig. 30) ; whereas in the rest of the epithelium two 

 kinds of cells are distinctly recognisable (PI. XXVI. fig. 31), 

 namely, {a) long, narrow, ciliated cells, and (6) gland-cells of 

 considerable size, whose bases project into the blood-sinus sur- 

 rounding the gut- wall. 



