470 F. W. GAMBLE. 



Whether they are zooxanthellse (as described by v. Graflf^ in 

 Enterostoma zooxanthellse), or food-remains, is a moot 

 point. Each eye possesses three lenses. The genital aperture is 

 ventral, a short distance in front of the hinder end. A pair of 

 testes lie at the sides of the pharynx; they lead by wide vasa 

 deferentia into a vesicula semiualis. The penis contains 

 proximally the separate granule-secretion and spermatozoa 

 separated; distally it is converted into a chitinous copulatory 

 organ, enclosing an inner muscular layer. The whole is bent 

 into an S-shaped curve. As in Pr. balticus, one portion of 

 the terminal margin is bent upon itself, and produced into an 

 extremely fine, needle-like spine. Germ aria and vitel- 

 laria as in Pr. balticus. A spermotheca is present near 

 the genital pore. 



Habitat. — Dredged off the " New Grounds,^^ Plymouth 

 Sound (F.W. G.). 



C. ALLCEOCCELA. 



The following definitions are v. Graff^s (53), as amended by 

 Bohmig (57, pp. 464-5) : 



Alimentary canal and parenchyma generally 

 sharply separated; a body-cavity absent in the 

 adult. Nervous and excretory systems present. 

 Testes follicular. Germ- and yolk-glands separate 

 or united, paired; the latter irregularly lobed, 

 rarely branched. Gonads contained in parenchy- 

 matous cavities without a membrana propria. 

 Penis formed by folds of the genital atrium. 

 No conspicuous chitinous copulatory organ. 



Family PLAGIOSTOMID^. 



Alloeocoela with pharynx variabilis (except Plag. 

 bimaculatum, where it is a pharynx plicatus), the 

 size and position of which is subject to varia- 

 tion. Genital pore single or double; sometimes 

 combined with the mouth. An otolith absent. 

 » 'Zool. Auzeiger,' 1886, p. 338. 



