CVU1 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, &c., previously 

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

 certain seasons, as a genital duct. 



Salensky, in his account of Loxosoma 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 Rhabdopleura 

 (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 

 inollusk. There seems to be no reason to doubt the 

 homological identity of these structures J. 



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

 genus Loxosoma : 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. G e se>. Zool. v. (1877), art. no. 3. 



t Allinan has taken a different view of the homologies of these organs. 

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

 Jihabdopleura," Journ. Linn. Soc. Zool. vol. xiv. p. 681. 



\ See Ray Lankester, " Remarks on the Affinities of Rhaftdopleura," 

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



