206 F. W. GAMBLE, B.SC. 



range up to 4 mm. Body similar to Acrorhynchus in shape, cylindrical, 

 bluntly pointed, in front, broader behind. Colour variable. Proboscis 

 usually white, the rest of the body dusky brown, through which the 

 testes, ovaries, and penis can be indistinctly perceived with a hand- 

 lens. Claparede (36) has described a variety from St. Vaaste-la-Hogue, 

 which was white with a median dorsal yellow streak. A similar 

 variety occurred at Plymouth (fig. 5). The colour was brown ; at the 

 base of the white proboscis and in the middle line was a yellow spot, 

 visible in all positions of the animal ; proceeding from this backwards 

 along the mid-dorsal line was a bright yellow streak. These colours 

 appear to be due to pigment in the parenchyma. Small rhabdites are 

 plentifully developed in the epidermis, and the epithelium of the 

 proboscis contains oval, highly refractive bodies, " Nematocysten 

 entsprechenden Gebilde " (v. Graff, ' Monogr.,' p. 323). The histology 

 and relations of the proboscis have been fully elucidated by v. Graff. 

 The brain, bearing two eyes provided with lenses, is placed behind 

 the proboscis, and behind this again is the spherical pharynx. The 

 common genital pore lies behind the centre of the body. It leads into 

 a very extensive atrium, the chitinous lining of which extends into 

 the common passage receiving an anterior male subdivision and a 

 posterior female portion. The testes occur at the sides of the body. 

 The vasa deferentia unite with the contents of an accessory gland. 

 The secretion of the granule-gland, however, is enclosed in a special 

 sac, the lower part of which is chitinous. Its free edge is usually 

 provided with a curved " spur," of variable form. This may be absent. 

 A remarkable variety is figured in PI. XL fig. 15. The ovaries, and 

 between them the large spermotheca, lie posteriorly. One egg-capsule 

 was present in many individuals at Plymouth in September. In 

 November no adults could be found. They had probably died off. 



Habitat. — Similar to Acrorhynchus caledonicus. The two are. 

 however, only occasionally found together. Plymouth Sound (F. W. G.); 

 Millport (v. Graff, "Ich selbst habe in Millport niemals grossere 

 Exemplare gesehen als Claparede's," p. 323, ' Monogr.'). 



Distribution. — This is the commonest Rhabdoccele at Naples, Lesina, 

 Messina, Trieste (v. Graff), Sebastopol (Uljanin), Black Sea (Czerniav- 

 sky), Madeira (Langerhans, MSS.). 



