ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 779 



kind distinguish this new form from any other Lycorid, while the 

 appearance of the parapodia recalls what is seen in the Hesionidse and 

 certain Syllidte ; in addition to this the presence of the third central 

 antenna is a Syllidean character. On the whole, therefore, Ano- 

 plonereis unites the Lycorididse with the Hesionidae and Polynoidse on 

 the one hand, and on the other with the Syllidea, which may be con- 

 sidered as being the ancestors of the whole group of Nereids, when 

 that term is taken in a wide sense. 



Elytra of Aphroditacean Annelids.* — Mr. W. A. Haswell has 

 investigated the structure and functions of the elytra or scales, the 

 possession of which is one of the most characteristic peculiarities of 

 the Aphroditacea. 



"With regard to the functions of the elytra the author distinguishes 

 (1) protection, (2) production of phosphorescent light, (3) sensation, 

 (4) respiration, and (5) incubation. 



The protective function is in some cases the predominating one. 

 Thus in Iphione the scales are of extreme density, and cover the entire 

 dorsal surface with a complete armour. In others, the scales, though 

 tough, are more readily detached, and in many instances do not com- 

 pletely cover the dorsal surface ; or are so delicate, and so readily 

 parted with when the animal is irritated, that their direct protective 

 action must be very slight. 



When certain species of Polynoe are irritated in the dark a flash 

 of phosphorescent light runs along the scales, each being illuminated 

 with a vividness which makes it shine out like a shield of light, a dark 

 spot near the centre representing the surface of attachment where the 

 light-producing tissue would appear to be absent. The irritation 

 communicates itself from segment to segment, and if the stimulus be 

 sufficiently powerful, flashes of phosphorescence may run along the 

 whole series of elytra, one or more of which then become detached, 

 the animal meanwhile moving away rapidly and leaving behind it the 

 scale or scales still glowing with phosphorescent light. The species 

 in which the phenomenon of phosphorescence occurs are species 

 characterized by the rapidity of their movements, and also by the 

 readiness with which the scales are parted with ; and it seems not at 

 all unlikely that the phosphorescence may have a protective action, 

 the illuminated scales which are thrown off distracting the attention 

 of the assailant in the dark recesses which the Polynoidaa usually 

 frequent. 



That the elytra act, like the dorsal cirri, as organs of some special 

 sense, seems probable from their abundant innervation, as well as 

 from the presence, in many instances, of fimbriae and other appendages, 

 some of which act as end-organs for the nerve-branches. 



In Aphrodita and Hermione the scales have been observed by 

 Williams and Quatrefages to perform an important mechanical 

 function in connection with respiration. In these genera the dorsal 

 surface is covered with a coating of felted hairs, which stretch across 



* Ann. and Mag. Nat. Hist., x. (1882) pp. 240-2. Proc. Linn. Soc. N. S. Wales, 

 vii. (1882) pp. 250-99 (6 pis.). 



