CVlll INTRODUCTION. 



Ehlers has noticed the nephridium in Hypophorella {op. 

 cit. p. 66) ; and I should place in the same category the 

 intertentacular organ of Alcyonidium, kc, previously 

 described^ which^ whatever its other functions^ serves^ at 

 certain seasons, as a genital duct. 



Salensky, in his account of Lowosoma crassicauda'^ , de- 

 scribes a more complex glandular organ, placed in the 

 parenchyma, on both sides of the intestine, and opening- 

 out on the surface of the body, which, he conjectures, 

 may have an excretory function. 



iii. The Epistome. — This organ is only present in the 

 freshwater Polyzoa ; but its homologue may, I believe, be 

 found in the so-called " buccal shield " of Rhabdopjleura 

 (see p. 578) ; and in both of them may be recognized, in 

 my judgment, the equivalent of the molluscan footf. 

 G. O. Sars has shown that in Rhabdopleura the '^ shield " 

 occupies the same position as the epistome of the Phy- 

 lactolcemata. Both these organs bear the same general 

 relation to the buccal and anal orifices and to the gill- 

 filaments or tentacles as the foot of the more typical 

 mollusk. There seems to be no reason to doubt the 

 homological identity of these structures % • 



iv. The Pedal Gland. — This organ occurs only in the 

 genus Lowosoma : in some species it is confined to the 

 larva; in others it is permanent in the adult. It is 

 situated at the base of the peduncle, and supplies the 

 secretion by which the animal is attached. It is inter- 

 esting as being, in all probability, the homologue of the 



* Ann. d. Sc. Nat. Cf ser. Zool. v. (1877), art. no. 3. 



t Allinan has taken a different view of the homologies of these oi-gans. 

 See his ' Freshwater Polyzoa,' p. 46, and paper " On the Relations of 

 BhcMopleura." Joui-n. Linn. Soc. Zool. vol. xiv. p. 581. 



\ See Eay Lankester, " Remarks on the Affinities of Rhabdo^leicra," 

 Quart. Journ. Micr. Se. xiv. (n. s.) p. 77. 



