486 F. W. GAMBLE. 



atrium. The germinal portions of both germ- 

 yolk-glands are fused together in the middle line 

 dorsally. 



51. MoNooPHORUM STRIATUM (v. Graff). 



Length 1 mm. Body cylindrical^ rounded in front, pointed 

 behind. Colour carmine to the naked eye. Under the 

 microscope, however, it is seen that the reticular pigment is 

 well developed, leaving the margins of the body and the outer 

 sides of the eyes almost free. The surface of the body has a 

 characteristic " streaked " appearance, caused by the grouping 

 of the longitudinal muscles into bundles of four to six. In 

 the intervals small rhabdites are plentiful. The cilia are very 

 strongly developed. Bohmig has discovered that the oral and 

 genital apertures unite. The pharynx is very contractile. 

 The spermatozoa are collected in a pair of vasa deferentia 

 and transferred to the globular base of the penis, the terminal 

 part of which is narrow and cylindrical. For a more detailed 

 account see Bohmig (57), pp. 435 — 447. 



Habitat. — Dredged in 4 fms. oflF the Duke Rock, Plymouth 

 Sound (F. W. G.). 



Distribution. — Trieste, among Ulva (v. Graff, Bohmig). 



Family MONOTIDiE. 



Alloeocoela with two genital apertures. A spermo- 

 theca present. Two germaria and two distinct 

 vitellaria. Testes follicular, closely aggregated 

 between the pharynx and the brain. Pharynx 

 directed posteriorly. An otolith present. Elon- 

 gate flat forms, with a narrow anterior end, and 

 a broad posterior extremity furnished with "ad- 

 hesive cells." 



