242 APHKODITA. 



Savigny in his ' Systeme ' l made the Aphroditidas the first family of his Nereidees, 

 characterised by having the branchia3 in the form of a ridge or papilla situated superiorly 

 at the base of the dorsal branch of the foot. They are absent from the second, fourth, 

 fifth, seventh, ninth, and eleventh pairs of feet, and so on until the twenty-third or 

 twenty-fifth. They determine by their absence that of the superior cirrus, and are 

 replaced by scales. The scales, when present, number from twelve pairs or fewer to 

 thirteen pairs or more, and extend to the twenty-third or twenty-fifth segments, and 

 are followed or not by supernumerary pairs. They are formed of separate membranous 

 lamellae, the upper thickened, sometimes horny, the inferior delicate, and attached by a 

 hollow pedicle to the base of the feet without branchias — in a position, however, corre- 

 sponding to the attachment of the latter. The mouth has a proboscis and four jaws. 

 The former is cylindrical, massive, striated transversely, and furuished with a fringe of 

 small tentacles at the orifice. The jaws are horny or cartilaginous, flat, short, more or 

 less free at the point, and have a vertical motion on each other. The eyes are four in 

 number, two anterior and two posterior. The antennas are retractile, elongated, 

 generally complete ; the median of two articulations, the first being short ; the unpaired 

 the same; the anterior always present and much larger than the others, finely ringed, 

 conical, and with tapered tips. The feet have either two divisions or these are united — 

 furnished with aciculi. Cirri prominent, generally composed of two chief divisions ; the 

 first, short and thick/lies at the base of the other, which is retractile. The superior cirri 

 are large, extending beyond the bristles, while the latter pass beyond the inferior cirri. 

 The first pair of feet have the divisions intimately united, without bristles or with 

 numerous bristles, and the two cirri elongated like tentacles. The second pair of feet 

 have also a long inferior cirrus, a little larger than the succeeding. The intestine is 

 provided with numerous ca3ca, which are most distinct in Aphrodita proper. Savigny, 

 from the foregoing, used the term (Aphroditidge) in its widest sense. 



In Cuvier's c Eegne Animal ' 2 (Mem. Edit.) M. Audouin arranged the Aphroditidse 

 and Polynoidae under the order Dorsibranchiata (corresponding to the Nereidees of 

 Savigny). 



Audouin and Milne Edwards (1834) classed the Aphrodisiens (which included 

 Aphrodita, Polynoe, Sigalion, and Palmyra) as the first family of their Annelides 

 Errantes, and they gave a description which defined the somewhat extensive group. 

 One important feature is the presence of a double row of membranous scales, the elytra 

 of Savigny, fixed on the dorsum by a pedicle to the superior division of the foot, and ac- 

 cording to the authors filled with ova at certain periods. They occur in some on 

 all the feet or on alternate feet, while in others they are absent. They refer to small 

 processes attached to the under surface of the scales as branchiae. Cirri occur on the 

 segments devoid of elytra, with the exception of Sigalion, where they are present on all 

 the segments. The feet are bilobed, each division being armed with a spine, bristles, and 

 cirri, the last existing on every foot ventrally. In the first segment the dorsal cirri 

 become tentacular cirri. The antennas are attached to the head, and are three in number 



1 ' Systeme des Annelides/ tome i, 3e part., 1820. 



2 MM. Audouin, &c, ' Regne An./ 1836-7. 



