100 mb. -r. c. punnett on [May 21, 



surrounded by a firie circular muscle-layer. Just in front of the 

 brain this lacuna divides into two limbs which almost immediately 

 reunite. Prom this junction is given off the median dorsal vessel, 

 which at once enters the proboscis-sheath. A little more pos- 

 teriorly the main lacuna gives off two large trunks — the lateral 

 lacunae, which extend over the cerebral organ and surround its 

 hinder portion. Almost immediately after giving off the lateral 

 lacuna' to the cerebral organ, the median lacuna ends by giving off 

 two lateral branches — the buccal lacuna?, which at once fuse with 

 the lateral lacunae in the region of the cerebral organ. The chief 

 points of divergence from the usual arrangement lie in the single 

 head-lacuna, and in the short course and large size of the buccal 

 lacunae. A similar cephalic lacuna has, so far as I am aware, only 

 been described among the Lineida? for L. sanguineus '. 



The backward extent of the rhynchocceloin relative to the body- 

 length cannot, owing to the imperfection of the specimen, be 

 given. The proboscis is slender, measuring in the smaller indi- 

 vidual not more than -75 mm. in cross-section. Its layers are 

 arranged in the following order — proboscis epithelium, nervous 

 layer, circular muscles, longitudinal muscles, rhynchocoelomic 

 epithelium. There are two ill-defined muscle crosses. 



The excretory system is extensive and possesses numerous ducts 

 on either side (Plate VII. fig. 10, exd.). Most of these make an 

 angle of about 45° with a line joining the nervous side-stems. 

 Some open nearer the level of the side-stems, though none open 

 more dorsally. The excretory tubules do not extend ventral to 

 the level of the nervous side-stems. Many of them project as long 

 tufts into the lateral lacunae, which here are easily distinguished 

 from the oesophageal lacunae. 



The brain is fairly well developed, the dorsal ganglia being half 

 as large again as the ventral. The dorsal commissure is very short, 

 and the ganglion-cells of the two dorsal ganglia here almost meet 

 dorsally over the proboscis-sheath. The dorsal lobe of the dorsal 

 ganglion does not reach as far as the commencement of the cerebral 

 organ. No neurochord-cells are present. 



The cerebral organ is not large. It lies directly over the side- 

 stems (Plate VI. figs. 1, 2, 3). It is rounded in transverse section, 

 and is almost completely sheathed in gland-cells. 



The head-slits are deep and end before the level where the 

 cerebral organ starts (Plate VII. fig. 10). The head-glands are 

 well marked dorsally and ventrally. Before the level of the brain 

 they merge into the cutis-glands. 



A small frontal organ of the typical Lineid form is present. 

 Eyes are absent. 



Synopsis of the Genus Amphiporus. 



By adding new species to the genus Amphiporus this paper raises 

 the total of the named species referred to that genus to over 40. 



1 Oudeman8, A. C. : loc. cit. p. 45. 



