578 ON SOME SOUTH PACIFIC NEMERTINES COLLECTED BY DR WILLEY. 



The colour of the preserved animal was a uniform dirty brown. A lighter area 

 extended along the edges of the head slits and round the proboscis pore (Fig. 41). 

 The mouth commenced after the posterior end of the head slits. No eyes are present. 



The head glands are fairly strongly developed, extending for two-thirds of the 

 distance between the brain and the tip of the head, where they open by several 

 small pores. 



The skin greatly resembles that of the Eupolidae in structure, the gelatinous layer 

 of the cutis (" Bindegewebeschicht " of Burger) being, at the end of the raid-gut region, 

 as thick as the rest of the cutis and epidermis together (Fig. 42). A similar condition 

 has been described by Blirger for L. geiiiculatus. 



With regard to the vascular system the two loops of the head-ring unite just in 

 front of the brain (Fig. 43 (a)). Just anterior to the level where the cerebral organ is 

 first seen and where the lateral nerves are given off the single vessel so formed divides 

 into four (Fig. 43 (c)), a ventral and a doi-.sal median vessel and two lateral vessels. 

 These two lateral vessels then take an upward course over the dorsal ganglion and, 

 after surrounding it, unite ventrally with one another and with the median ventral 

 vessel (Fig. 43 (e)). The median ventral vessel here disappears and the lateral vessels 

 form large sinuses reaching more than half-way round the cerebral organ (Fig. 43 (f)). 

 From these sinuses the lateral blood vessels of the trunk are eventually given off. 

 Meanwhile the median dorsal vessel enters the proboscis sheath (Fig. 43 (f)). 



The excretory pore opens very shortly after the termination of the cerebral organ, 

 opening laterally from an excretory duct which passes just over the lateral nerve. 

 Only one pore occurs on each side. The excretory tubules all lie anterior to it and 

 on the dorsal' side of the great blood sinus surrounding the cerebral organ. The 

 whole extent of the system is small being only '3 — "4 mm. in the contracted 

 specimen. 



The head slits are very deep, the distance between their termination and the 

 brain being only one-twelfth of the depth of the slit. The general characters of the 

 brain call for no special comment. They are shewn in (Fig. 43 (a) — (f)). 



A frontal organ is not present. 



10. Li'neus alho-vittutus BuRGER, 1890. PL LXI. Figs. 46—47. 



A single specimen lacking the hind end was taken at Lifu. Length about 18 cm. 

 when alive. The colour of the living animal was a dark black green. On the dorsal 

 surface of the head there was a zigzag line of a pale greenish white hue (Fig. 47). 

 In spirit the appearance of the animal greatly resembled the figure given by Burger 

 ((1) PI. I. Fig. 1), being characterised by the small size of the head and the enormous 

 mouth, as well as by the colour and head marking. 



In internal anatomy it also agrees with Biirger's description, the peculiar small 



' A dorsal position for the excretory system has been described by Biirger for L. gilvus, L. pdrviilus, and 

 L. gesserensis, but in all these cases the excretory pore is not lateral but dorsal in position. Moreover the 

 species here described differs from all tliese three in various points, e.g. structure of skin, size of head slits, 

 size, absence of eyes, &c. 



