BRITISH MARINE TUHBELLARIA. 457 



it and the hinder end is the genital aperture. The large 

 testes occupy the middle of the sides of the body. The vasa 

 deferentia are swollen just before uniting at the base of 

 the retort-shaped penis which receives the secretion of 

 granule-glands. The copulatory organ is a compli- 

 cated mechanism of chitinous pieces separating the granule- 

 secretion from the spermatozoa. The nutrient part of the 

 germ-yolk-gland extends along the sides of the body; the 

 ovarian portion develops behind the pharynx. The two ovi- 

 ducts unite, and the common duct runs to the genital pore. 

 Opening into the atrium, close to the pore, is the large 

 spermotheca, which is directed forwards towards the pharynx, 

 and then bends back upon itself. Its blind end receives 

 chitinous ducts conveying granule-secretion. The point of 

 connection with the genital atrium is armed with five to six 

 triangular chitinous teeth, freely hinged at their bases. A 

 further account of these structures will be found in v. Graff 

 (pp. 277 — 279) and Jensen (49). The above are points I have 

 verified myself. 



Habitat. — Several feet below surface and in tide-pools. 

 Millport (v. Grafi"); Plymouth (F. W. G.); common among 

 Ptilota plumosa and other red and green algae, low spring 

 tide, Port Erin, Isle of Man (F. W. G.). 



Distribution. — West coast of Norway (Jensen). 



18. Proxenetes cochlear, v. Grafi'. 



The four or five chitinous ducts of an accessory gland, 

 which open into the blind end of the bursa in P. flabellifer, 

 are, in this species, reduced to a single spiral one ; the 

 triangular "teeth," arming the duct of the bursa, being here 

 represented by a series of small chitinous processes. The 

 copulatory organ consists of three spoon-shaped pieces fitting 

 into one another. The spaces between them constitute the 

 passages for the seminal and granule fluids. 



Habitat. — Millport, one specimen (v. Grafi'). 



VOL. XXXIV, PART IV. NEW SER. H H 



