452 p. W. GAMBLE. 



I have described them as seen in Pr. solea. Pharynx in the 

 posterior third of the body. Behind it lies the penis, which 

 is pyriform, its upper part filled with spermatozoa. The 

 duct is chitinous. 



Habitat. — This species is found rarely in 5 — 15 fms. Ply- 

 mouth Sound (F. W. G.). 



Distribution. — Messina, Naples (v. Graff), Lesina 

 (Schmidt), Egedesminde, Greenland (Levinsen). 



12. Promesostoma solea (O. Schmidt, 32). 



Differs from the preceding species in two points. The 

 reticular pigment is less dense, and the pigment-cup of the 

 eye sends a hooked process over the outer surface of the lens. 

 The latter point alone seems to me to be constant. The 

 amount of reticular pigment varies greatly. Seen from the 

 dorsal surface the eye has an appearance similar to a miniature 

 pan or tobacco-pipe, the bowl being represented by the 

 pigment-cup, and the stem or handle by the strip of pigment 

 running over the lens. The vibratory movement of the eye is 

 performed in the following way. Suppose the pan or pipe to 

 vibrate through a small angle in its plane of symmetry, in 

 such a way that the plane is horizontal, the bowl moving for- 

 wards and then backwards. The actual vibrations of the eye 

 are of this kind. Apparently one eye commences, performs 

 five or six vibrations in a second, and then stops; the other 

 eye begins, and so on. I am not certain, however, that the 

 movements are alternate for any length of time. Of the 

 mechanism I am ignorant. 



Habitat. — This is a typical deep-water (8 — 20 fms.) Tur- 

 bellarian. Only once have I taken it between tide-marks. 

 When dredge-material is placed in sea water, dark oval specks 

 (the present species) are often seen swimming actively at the 

 surface. In a few hours they descend, and reappear only when 

 the water begins to foul. Plymouth (F. W. G.). 



