.NEMERTEANS. Ill 



usually the case, whilst here it gives off a strong proboscis sheath nerve ("untere Riicken- 

 nerv "). Shortly afterwards it dips down to lie in the normal position between the outer 

 longitudinal and circular muscles. A similar arrangement, though much more marked, occurs 

 in Oxypolia beaumontiana^. 



The cerebral organ is small and for the most part much compressed (PI. V. fig. 7). 

 It possesses a very scanty supply of glands. The head slits are deep, reaching nearly to 

 the brain. They end abruptly where the ciliated canal comes off. 



The head glands are fairly well marked. The frontal organ is very small. Eyes absent. 



9. Lineus albovittatus (Stimpson, 1857), Burger, 1890. 



Locality. Hulule, Male atoll, Maldive Is. From reef. 



One specimen measuring 15.5 mm. in length and 8 ram. in breadth. Its wide distri- 

 bution has already been noted-. 



10. Prosadenoporus huergeH, n. sp. 



Locality. Minikoi, Laccadive Is. From beneath a stone in the boulder zone of reef. 



A single specimen was obtained. Length after preservation, 70 mm.; breadth, 2'5 mm. 

 The breadth is uniform throughout, and the body is rounded in external appearance. The 

 proboscis was extruded, and measured 35 mm. in length and 1'5 mm. in breadth. Colour 

 in life pink-white. 



The epithelium rests on a well-marked basement membrane. The circular muscle layer 

 is considerably thicker than the basement membrane, and is well developed for a meta- 

 nemertean. The longitudinal muscle layer is several times as thick as the circular layer. 



The oesophagus and rhynchodaeum are fused together a little way behind the common 

 opening which is situated nearly terminally on the ventral surface. There is no well- 

 marked ventral blind gut, but where the oesophagus passes into the intestine a single 

 lateral diverticulum is given off from the latter on either side. These two diverticula are 

 spacious and, lying on either side of the oesophagus, extend forwards nearly to the region 

 of the brain. The intestinal diverticula are wide and shallow. 



The vascular system presents the usual metanemertean arrangement. 



The proboscis sheath extends to the hind end. It possesses an inner layer of longitu- 

 dinal muscles surrounded by a layer of circular ones. The proboscis is formed on the usual 

 metanemertean plan. It contains 19 nerves. 



The excretory system is absent. 



The gonads are comparatively undeveloped. They are small sacs containing minute ova. 

 The genus is stated by Burger to be hermaphrodite, but no traces of testes were to be 

 distinguished in this specimen, though in the other species of the genus this author found 

 ova and spermatozoa both ripe at the same time. 



The brain is not large and I have been unable to distinguish neurochord cells. The 

 small cerebral organs lie ventral to and entirely in front of the brain. They open on the 

 ventral surface. 



1 K. C. Punnett, Quart. Journ. Mic. Sc. Vol. 44 (in the - B. C. Punnett, Proc. Zool. Soc. 1900, p. 826. 



press). 



