BRITISH MARINE TURBELLARIA. 489 



ings. Pharynx, brain, otolith, and eye as in M. lineatus. 

 The male pore is placed further forward than in the latter 

 species. The vasadeferentia open into the neck of the very 

 muscular vesicula seminalis. The copulatory organ is a 

 hollow chitinous spine of variable shape, connected at its base 

 by muscles to the wall of the seminal vesicle. Numerous 

 accessory glands open at this level. The spermatozoa are 

 whip-shaped, the handle being stout, the lash a very fine thread. 

 Opening to the exterior through the female genital pore is the 

 spermotheca, provided, according to v. GraflF and Jensen, with 

 secondary lobes. The remaining parts of the female genital 

 apparatus do not materially differ from those of M. lineatus. 



Habitat. — This species extends its range to the higher parts 

 of the littoral zone. In consequence it is liable to be exposed 

 to the air for some hours. Many of its devices for obtaining 

 a moist position during ebb-tide have been described by Hallez 

 and V. Graff. Thus the former observer collected Balani, the 

 latter Chitons and Patellae at low tide. After placing these 

 in sea water, Monotus fuscus crept out of gills or thoracic 

 limbs as the case might be. In the Isle of Man I have found 

 them nestling among the appendages of Balani. Millport 

 (v. Graff) ; Port Erin, and Plymouth (F. W. G.). 



Distribution. — Faroe Islands (Schmidt, 24), Bergen (Jen- 

 sen, 49), Droback and Denmark (Oersted, 16), Heligoland 

 (v. Graff), Cuxhaven in the Baltic (Schultze), Ostende (van 

 Beneden [33] and v. Graff), Wimmereux (Hallez, 50). 



54. MoNOTUs ALBUS, Lcviusen (51). 



Length TS mm. (i. e. half that of Levinsen's specimen). 

 Body elongate, narrow, the hinder end not expanded into a 

 disc, colourless ; the contents of the gut reddish. Ocular pig- 

 ment absent. Pharynx posterior. A large spermotheca 

 containing a refractive secretion opens to the exterior in front 

 of the penis, which is armed with a shoe-shaped chitinous 

 copulatory organ, bearing a couple of lateral teeth on the 

 free margins. 



VOL. XXXIV, PART IV. — NEW SEB. K K 



