470 M. Pierre Fauvel on the Homology of the 



LXXII. — Homology of the Anterior Segments q/'Ampharetidae 

 {Polychetous sedentary Annelids). By M. Pierre 

 Fauvel *. 



The anterior segments of the bodies of the Ampharetidse 

 appear to be difficult enough to homologize if one relies on 

 the descriptions given by authors, for these are frequently 

 contradictory. Malmgren f has distinguished in the species 

 which he has described : — (1) a cephalic segment ; (2) a 

 buccal segment ; (3) a naked segment ; (4) a segment (ac- 

 cording to him the third) which carries the paleas in those 

 species which are provided with these special hairs, as well 

 as the first pair of branchige ; (5) the first segment carrying 

 the capillary hairs, followed by segments of like character. 

 The branchia3, to the number of four pairs (rarely three), are 

 borne, according to the species, either solely by the fourth 

 segment (third of Malmgren, 3Ielinna), or by the fourth and 

 the fifth {Ampharetes) , or by the fourth, fifth, sixth, and some- 

 times by the seventh segments [AmpMcteis) . The first three 

 segments may sometimes be invaginated on the fourth. This 

 easily explains the errors of those authors who, having under 

 observation only fixed and contracted specimens, have not 

 recognized the presence of a segment behind the buccal 

 segment. This error is least to be explained in the case of 

 Clapar^de :):, who has overlooked this segment in Amphicteis 

 curvipalea^ which nevertheless he had alive under his hands. 

 He only reckons a single achetous segment, and erects the 

 absence of the second naked segment into the principal 

 difiference between A. curvipalea and A. Gunnert\ Sars. 

 Now, as we have been able to determine ourselves on 

 several examples from Naples, this segment positively exists. 

 The description of ClaparMe is, besides, erroneous, as well as 

 his figure §. We have found Amphicteis Gujineri, Sars, at 

 Saint- Vaast-la-Hougue in 1894 ||. Prof. A. Wiren has since 

 been kind enough to send us specimens of A. Gunneri from 

 the coasts of Sweden. We have thus been enabled to deter- 

 mine the complete identity of specimens from Naples, 

 Sweden, and the Channel. 



The species of Clapar^de founded on erroneous observa- 

 tions ought to disappear. The only difference consists in the 

 absence, not constant, of a seventh tooth on the uncial plates of 



* From the ' Comptes Rendus,' 1896, torn, cxxiii. pp. 708-710. 

 t Malmgren, * Nordiska Hafs-Annulater,' 1865. 

 j Claparede, ' Ann^lides du Golfe de Naples,' Supplement, 1870. 

 § IjO Bianco, ' Gli Annelidi Tubicoli trovati nel Golfo di Napoli,' 1893. 

 II P. Fauvel, " Sur la Presence de V Amphicteis Gunneri sur les cotes de 

 la Manche " (Bull. Soc. Linn, de Normandie, 4' s6rie, 9' vol., 1895). 



