570 ON SOME SOUTH PACIFIC NEMERTINES COLLECTED BY DR WILLEY. 



1. Carinesta orientalis, n. sp. Plate LYII. Figs. 1 — 9 and LVIII. Figs. 10 — 11. 



Two specimens were procured from Pigeon Island, New Britain, the larger of 

 which, though lacking the hind end, measured about 16 cm. in length and was about 

 2'5 mm. thick. The smaller specimen was still more imperfect, but the whole of the 

 anterior portion of the body was preserved in each case. The colour was a uniform 

 dull red-brown, becoming rather lighter towards the anterior end. There were no 

 markings of any sort. 



The mouth is large and is situated shortly behind the brain. The small proboscis 

 pore is ventral and nearly terminal (Figs. 1 and 11). -The epidermis is not very 

 thick and contains a number of unicellular glands. Composite glands are absent, and 

 there are no glands beneath the basement membrane such as occur in the genus 

 Carinella. Directly beneath the thin basement membrane a very delicate nervous layer 

 can be made out. In front of the brain this becomes greatly thickened, suggesting 

 a tactile function for the elongated pre-cerebral portion of the head (Fig. 3, n.l.). 



The circular musculature is feebly developed and is lacking in the region of the 

 brain. 



The inner circular musculature which envelops the proboscis sheath and ali- 

 mentary canal starts behind the movtth. It encloses also the blood vessels at first 

 but these soon come to lie outside it, and a special portion then surrounds the 

 proboscis sheath (cf. Figs. 6 and 7). There is a slight dorsal decussation of fibres. 



The longitudinal musculature is well developed throughout. The portion surround- 

 ing the proboscis sheath is throughout the course of the latter well marked off from 

 the rest, and with the differentiation of circular fibres round it comes to lie external 

 to these last (Figs. 4, 5, 6 and 7, m.l.jj.s.). 



The alimentary canal is straight without any caecum or pouches and appears 

 relatively large with very high epithelium towards the hinder end of the body. 

 In the anterior part of the oesophageal region it has special longitudinal muscles 

 which lie dorsally within and ventrally without the circular muscles (Figs. 5 and 6, 

 m.l.oes.). 



The proboscis is attached just behind the brain (Fig. 11), and possesses a thick 

 epithelium together with an outer circular and an inner longitudinal muscle layer 

 (Figs. 10 and 11), the latter being covered by the delicate rh}Tiehocoelom lining. 

 The two proboscis nerves lie just outside the circular muscles. There are well-marked 

 glands in the rhynchodaeum near the proboscis pore (Fig. 11, gl-p-). 



The vascular system consists of two longittidinal lateral trunks which meet anteriorly 

 dorsal to the proboscis pore. In front of the brain they give off a ventral and a 

 dorsal vessel, the former of which joins the loop over the proboscis whilst the latter 

 ends blindly (Figs. 2 and 3). An anastomosis between the two vessels of the head 

 loop has been figured by Joubin for Carinella hanyulensis ((6) PI. XXVII. fig. 8), 

 though it is of a simpler nature and only dorsal. Small vessels are given off to the 

 oesophagus, but there is no dorsal vessel to the proboscis sheath. 



The excretory system is small and consists of a glandular portion lying inside 

 the lateral blood vessel as in Carinella, and a small duct opening more posteriorly 



