7 J 

 2. Cliottopsis luicroccphalns n. sp. (PI. V, figs. 126 — 128). 



Living animal: 



Stat. 259. 5°29'.2S., 132° 52'. 5 IC. I spec. 



Body: elongated, truncated at the posterior end. Skin williout pigment, transparent, 

 with a great many small, brown glands, which are placed in groups of three or four together. 

 Two systems of crossing lines (muscular fibres) are visible on some parts of the skin. \'isceral 

 nucleus extending to the posterior e.xtremity. The connective tissue, consisting of branched cells, 

 between the nucleus and the skin especially well developed. The body is somewhat compressed, 

 showing a constriction in the anterior part, beneath the fins. I have seen no dorsal spot. 



Head: small ; neck short. 



Foot: the anterior lobes are thick, and muscular; posterior lobe absent, as in the. 

 other species of the genus. Tubercle well developed, oval, consisting of five or si.\ lamellae, 

 longitudinally placed. Anterior lobes terminating distally in an acute angle. 



Fins: small, rounded (they are strongly contracted in the single specimen collected). 



Posterior gill: wholly absent; at the aboral pole, however, of the body at the 

 place of the gill, the genital gland is situated, at the outside of the body, somewhat turned 

 to the right. It consi.sts of numerous rounded follicles which in microscopical examination 

 show some ova with a very large nucleus, and a great many rounded cells, imbedded in 

 fibrillar connective tissue. A thin, brownish-coloured efferent duct arises from the g-land towards 

 the accessory genital glands, situated ventrally. The curious arrangement of the genital gland 

 at the outside of the body seems perhaps abnormal (due to fixation .?), but it is more probable 

 that it is the normal position in the living animal, as I could not observe any rupture in 

 the body -wall, and the internal organs did not exhibit any displacement. 



Hook-sacs: very .shallow, each wath about twenty hooks, bunch-like arranged. 



R a d u 1 a : the formula is 4 . i . 4. The median tooth is tricuspid, as in other Clionopsidae, 

 but at both cornua of the semi-lunar tooth a small projecture may be seen (fig. 128). The 

 lateral teeth are well developed, with broad base and strong beak, slightly bent at the extremity. 



Proboscis: very long, laid in wide windings, when invaginated ; about as long as 

 the animal it.self. It occupies the whole anterior portion of the visceral mass, while the posterior 

 part is filled up by the stomach and the liver. 



Colour: yellowish, nucleus visible as a dark, thick bar (spirit-specimen). 



Length: 15 mm. 



Remarks: The general form of the body, the transparency of the skin with its systems 

 of crossing lines, the absence of a gill whose function seems to be adopted by the genital 

 gland, the longitudinal lamellae in the tubercle between the anterior lobes of the foot, the 

 small number of hooks in the hook-sacs, and the formula of the radula — alle these peculiarities 

 are sufficient to take it for granted, that the specimen of the Siboga is a new species. It 

 seems even admissible to regard it as the representative of a new genus (characterised by the 

 absence of a gill, and the conformation of the genital gland), but as I could study only this 



SIEOOA-EXPEDITIE UI. lO 



