HOPLONEMERTINI 



Hubrecht 1879. 



Surface epithelium in single layer. Two layers 

 of musculature in the body wall. Mouth opening 

 in front of or below the brain. Intestine straight. 

 Intestinal caecum and diverticula developed. Nerve 

 system in the parenchyma. Cerebral organs -- if 

 present - - separate from the brain. Proboscis 

 with a highly developed armature. Blood lacunae 

 lacking. 



MONOSTILIFERA nov. subordo. 



Hoplonemerteans with one stylet on the stylet 

 basis. 



POLYSTILIFERA nov subordo. 



Hoplonemerteans with several stylets on the 

 stylet basis. 



Reptantia nov tribus. 



Polystilif era living on the bottom. Cerebral 

 and nephridial organs and diverticula on the pro- 

 boscis sheath developed. 



PelaglCa nov. tribus. 



Pelagic polystilif era. Cerebral and nephridial 

 organs, diverticula on the proboscis sheath and 

 metameral transverse vessels lacking, d* sexual 

 glands confined to the head region. 



Bathynemertidae nov. fam. 



Medium sized pelagic nemerteans. Body not 

 particularly broad and only slightly flattened. 

 Hinder end without caudal fin. Stomach and 

 intestinal caecum large. The intestinal diverticula 

 with ventral branch; between this and the dorsal 

 are placed the lateral nerve and blood vessel. The 

 muscular system of the body wall much reduced. 

 The muscular wall of the proboscis sheath consists 

 of interwoven circular and longitudinal muscle 

 fibres. 



Bathynetnertes nov. gen. 



Body tapered at both ends. Mouth and pro- 

 boscis pore united. The proboscis sheath extends 

 throughout the whole length of the body. Many 

 eggs are developed in the ovaries. 



Bathynetnertes Hubrechti nov. sp. 

 (Plate I, Fig. 5.) 



As shown in the figure, the shape of the body in 

 this species is only slighthly affected by the pelagic con- 

 ditions, there being still considerable resemblance to the 

 Drepanophoriis species of the bottom, from which all 

 known pelagic nemerteans are derived. 



Length 56 mm. greatest breadth 10 mm. greatest 

 thickness 5.5 mm. The surface epithelium slightly, the 

 basement layer very strongly developed. 



The tip of the snout forms a funnel-shaped depres- 

 sion at the bottom of which lies the proboscis pore, the 

 mouth opening being a broad transverse fissure in the 

 ventral wall of the funnel. An oesophagus being absent, 

 the mouth opening leads directly into the stomach which 

 is developed to an unusual degree with highly folded 

 walls, permitting a considerable expansion; its length is 

 about 3 mm. Behind the brain it leads gradually into 

 the pyloric tube which is no less than 8 mm. long. 



The intestine is narrow, and furnished with about 

 40 pairs of large lateral pouches or diverticula which 

 are highly ramified, the ramification proceeding from a 

 dorsal and a ventral main branch. The intestinal caecum 

 is well developed: it has a length of 8 mm. and is fur- 

 nished with five pairs of diverticula, likewise highly ramified. 



The proboscis is surprisingly strong, but relatively 

 short, its length not exceeding that of the body. Its wall 

 contains 29 proboscidial nerves. Structure of the stylet 

 apparatus as in Drepanophoriis. The rhynchodaeum is 

 very short; the proboscis sheath however, may be found 

 extending right out into the point of the tail. The muscu- 

 lature in the wall consists of a network of interwoven 

 circular and longitudinal fibres, exactly as in Drepano- 

 phoriis. 



The specimen in question is a young ? with ovaries 

 not yet fully developed; they lie between the pouches of 



