ON SOME SOUTH PACIFIC NEMERTINES COLLECTED BY DR WILLEY. 577 



The proboscis sheath is small and of the usual type. Just over the proboscis 

 vessel the epithelium becomes high and glandular (Fig. -iO, psjjl.). 'J'he proboscis 

 is lost 



The wall of the mid-gut consists of two well-marked portions, the inner ciliated 

 epithelium and the outer glandular portion, such as has already been described by 

 Hubrecht for one of the "Challenger" species {E. nipponensis). The vascular system 

 consists in the snout of wide laterally extending lacunae lying dorsal to the proboscis 

 sheath (which here of course is morphologically proboscis epithelium of ectodermal 

 origin) (Fig. 36, b.v.). In the brain region the vascular system comes to lie ventral 

 to the proboscis sheath and comprises a large median and two small lateral vessels 

 (Fig. 37). Further back the lateral vessels become enlarged and sink down towards 

 the oesophagus (Fig. 38), in which region they break up into the plexus so characteristic 

 of the genus (Fig. 40). 



The excretory system is peculiar. Not only are there a great number of ducts 

 (probably 20 — 30 on each side), but the excretory gland is broken up into a immber 

 of portions. Numerous ducts have been described for E. (jiardii by Hubrecht (6) and 

 for E. curta by Oudemans (9), but the gland was always continuous. The only other 

 case of a discontinuous gland among the Heteronemertini is that recorded by Coe (5), 

 p. 498, for Valencinia, but the phenomenon was far less marked in that case. A 

 reconstruction of the system is given in Fig. 35. Unfortunately this is not quite 

 complete as some sections containing the most posterior portion were lost. It could 

 not have extended much further backwards however as it is not found in sections 

 about 2 mm. posterior to the last shewn on the reconstruction. Hubrecht ((6), p. 116) 

 lays some stress on the correspondence of the ducts on the two sides. It will be seen 

 that practically none exists here. 



The brain is small for the size of the animal, and the dorsal ganglion is larger than 

 the ventral. 



The ventral commissure is strong (Fig. 37). 



The cerebral organ contains a pigment mass. It communicates with the exterior in 

 the head furrow ventrally (Fig. 37). The peculiar epithelium of the ciliated canal of the 

 cerebral organ is continued into and all round the head furrow (Fig. 37, ep.h.f.). 



8. Eupolia, sp. 



Fragments of a large white Eupolia were found by Dr Willcy living in sand 

 together with Ptychodera at Rakaiya. As the anterior portions of both the specimens 

 preserved were unfortunately missing it is impossible to give any further account of 

 the species. 



9. Linens au.stndis, n. sp. PI. LXI. Figs. 41 — 44. 



A single specimen from Lifu. The jtosterior portion of the body is broken off, so 

 that it is impossible to say whether it possessed the small tail which forms the chief 

 criterion, as regards external features, between the genera Lineits and Cerebratulus. 



The structure of the skin however, which resembled that of the genus Eupolia, 

 probably settles its position in the genus Lineus. 



