202 F. W. GAMBLE, B.SC. 



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

 (v. Graff); Plymouth (F. W. G.) ; common among Ptilota plumosa and 

 other red and green algse, low spring tide, Port Erin, Isle of Man 

 (F. W. G.) 



Distribution. — West coast of Norway (Jensen). 



18. Proxenetes cochlear, v. Graff. 



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. Graff). 



Subfamily EuMESGSTOMiNiE. 



Mesostomidoi with one common genital pore, a single germarium, two 

 vitellaria and accessory organs. Testes long. Excretory vessels 

 opening into' the pharyngeal sheath. 



Genus 10. Mesostoma, Duges. 



Without otolith. Copulatory organ traversed throughout its entire 

 length by the ducts of male secretions. 



19. 1 Mesostoma neapolitanum, v. Graff. 



Length '5 mm. Body flattened behind, bluntly pointed in front, 

 white. Between the eyes are two tracks formed by masses of large 

 curved rhabdiles. Smaller ones are present elsewhere. Pharynx 

 small, in front of the centre. Intestine large, filling up the greater 

 part of the body. Eyes two, with lenses. Genital pore, close to the 

 hinder end. Testes lateral. The penis bears a funnel-shaped terminal 

 portion which receives the contents of the vesicula granulorum, and in 

 front of this lies the semi-lunar vesicula seminalis. The atrium did 

 not appear to be so large as in v. Graff's specimen. 



