766 on THE CM.i:T080MATlD^, 



the alimentary canal, and opening by a pore at the posterior 

 extremity of the tail, is evidently excretory in function. Glands 

 of some kind are also present in the head-region of some, if not 

 all, the species, lying above the pharynx. They appear to be 

 connected with the hollow, dorsal, locomotor seta?. 



Some species show traces of a nervous system, in the shape of 

 an ill-defined ring round the pharynx. 'I'he peculiar, lateral 

 grooves on the rostrum are probably sense-oi'gans of some kind. 

 In the possession of a 'tail-gland,' and these lateral grooves, the 

 Chcetosomaiidce resemble many free-living, marine Nematodes. 

 The resemblance is discussed in the detailed description of Ch. 

 falcatum. 



The sexes are separate. In the male, a single, simple tube 

 extends from the anterior region to open with the rectum at the 

 anus, and two, equal, penial setae are present The female 

 sexual organs consist of paired ovaries, anterior and posterior, 

 each opening by an oviduct into a common uterus. 'J'he female 

 genital pore is situated on the ventral surface, about or in front 

 of, the middle of the body. The ova are relatively few, and 

 fairly large; and the animal appears to be oviparous. 

 Desckiptions of the Species. 



CH.ET0S0MA FALCATUM, n.Sp. (PlatcS xliv.-xlv.). 



A few individuals of this species were found in 1914, by Pro- 

 fessor Haswell, in material collected at Cremorne, Port Jackson; 

 and the majority of the specimens, which I have obtained since, 

 have come from the same locality. I have obtained only four 

 specimens elsewhere; one in material from Vaucluse, in which, 

 also, I found N. tenax; and three from the rocks between tide- 

 marks at Long Reef, a very exposed portion of the ocean-coast. 

 AX> Cremorne, they were all taken from among the growth of 

 shells and seaweed on a vertical rock-face, at a depth of from 

 4-5 feet below low water mark. They are scattered very sparsely 

 through the material, and the search for them is a lengthy one, 

 necessitating a preliminary fixation; and I have not yet been 

 able to obtain any living specimens. 



Ch. falcatum is an elongated, approximately cylindrical, worm- 

 like animal, greyish-white in colour. In length, it does not 



