APHRODITA. 245 



The feet are biramous, bearing scales or tentacular cirri, in general only the one or 

 the other. The ventral cirrus occurs on all the feet. Some have a resplendent covering 

 of hairs, and a felt-like coating on the dorsum protecting the scales. Those without 

 such sometimes show a radiate arrangement of the bristles. In the scales he describes 

 a lacunar system in connection with the general cavity of the body, and therefore he 

 thinks Savigny was right in associating them with respiration, though he was so far 

 misled by a balloon-like condition in imperfectly preserved specimens. He does not 

 regard the elevated and ciliated processes on the dorsum of the feet as branchiae, for 

 they have no central vessel and no lacunae, and the cutaneous tissues present no special 

 modification. On the other hand, De Quatrefages saw in the pretended branchial function 

 of the branching digestive system an analogy with what he had formerly described in the 

 iEolidae as phlebenterism. 



The circulatory apparatus he says agrees with the typical condition, but is difficult 

 to follow, as the blood is pale. There are dorsal and ventral vessels as described by Trevi- 

 ranus, and a third considerable trunk accompanying inferiorly the abdominal nerve-chain. 



The cephalic ganglia are comparatively large, and the exterior thereof brownish red. 

 The ventral chain has the ganglia united, though in general the two halves are distinct. 

 No commissure exists between the lateral ganglia of the first three pairs of feet — a condi- 

 tion absent in the Polynoidae. The visceral system of nerves consists of a muscular 

 trunk and a ganglion with a connective joining the brain. It supplies the muscles of the 

 proboscis. 



The only remarks the author makes in regard to the reproduction of the group is 

 that in a large number of examples of Ajphrodita hystrix he found irregular mounds con- 

 sisting of eggs enveloped by delicate tissue along the digestive canal and touching the 

 body-wall. These individuals consequently showed a large number of ova or of sperms 

 in the perivisceral cavity. Further, in a male he observed sperms escape as a white 

 thread at the base of the ventral division of the foot about the nineteenth segment. 



The classification adopted by De Quatrefages was based for the most part on 

 external characters, such as the arrangement of the scales, the absence, alternate or con- 

 tinuous condition of the dorsal cirri, the nature of the antennae (tentacles), and the jaws. 



In his general remarks on the Aphroditidae, Claparede 1 corrects the error of 

 Williams that vibratile cilia are absent from the peritoneal surface of Aphrodita aculeata. 

 This author was, however, in doubt concerning the vascular system, for though he found 

 a dorsal and a ventral vessel according to the old observations of Pallas and Treviranus, 

 yet he could not satisfy himself that they pertained to the vascular system. He makes 

 a few remarks also about the respiration in the group, stating that in Hermione hystrix, 

 during the alternation of expansion and contraction, the last pair of scales in the latter 

 function are raised, and a powerful stream of water sent out. The same is seen, though 

 to a much less notable extent, in A. aculeata. In the latter species bubbles of air 

 sometimes accompany the currents, so that Swammerdam had some foundation for the 

 remark that the Aphroditae swallow (gorgeant) air. He had, however, overlooked the 

 observation of Sir J. G. Dallyel when he said former authors had not observed these 

 respiratory movements. 



'Ann. Chet, Napol./ 1868. 



