NEREIDS. 253 



filiform dorsal cirri ; feet of. two divisions, branchial lobes at the extremity of the feet; 

 tentacles dissimilar; two jaws. In this description the lobes of the feet were termed the 

 branchiae, and the great vascularity of these in certain forms renders the interpretation 

 physiologically correct, though it is not necessary to place them on the same footing as 

 those with special branchial organs attached to the dorsal cirri. 



Grube 1 (1850) grouped the Nereids under his fourth family, Lycoridea, Savigny 

 s. str., two genera only being given, viz., Nereis and Lycastis, but he subdivided the first- 

 mentioned into three divisions according to the structure of the feet. The family was 

 placed between the Eunicea and the Nephthydea, and next year 2 he gave a synopsis of 

 the genera and species, basing his distinctions on the head and tentacles, the structure of 

 the feet, and the proboscis. 



Dr. Johnston did much in his earlier papers to elucidate the British forms, and in 

 the Catalogue of Worms in the British Museum (1865) he gave an excellent summary of 

 the history and general characters of the group ; but at that elate the relationships of the 

 heteronereid phase were obscure, and they were regarded as forming a distinct genus. No 

 less than fourteen species are entered in the Catalogue, which does not include either 

 Mieronereis or Leptonereis ; but of the list five are Heteronereids, though one of these refers 

 to a species not entered elsewhere, viz. Nereis (Eunereis) longissima, giving in all six Nereids 

 which stand. An examination of his collection in the British Museum 3 showed that JV". 

 fimbviata included various forms such as N. d< 'versicolor, N. pelagica, and N. Marionii, but 

 in all probability they had been mixed after his death. Nereis imbecillis was found in 

 1872 to be a Nereilepas with the paragnathi for the most part absent. It is uncertain 

 what the Nereis pidsatoria of Montagu and mentioned by Dr. Johnston is. The foot 

 as figured by Audouin and M. Edwards somewhat resembles that of Nereilepas, but the 

 arrangement of the paragnathi diverges. 



Dr. T. Williams i considered that the Nereids had a large amount of " milky 

 perivisceral fluid," which fluctuates from one end of the body to the other. The 

 corpuscles, he says, are superseded by true ova in autumn. The same author 5 

 describes the segmental organs in Nereis margaritacea as consisting of a tube, richly 

 ciliated, both ends of which open externally, the ingoing dorsally and the longer outgoing 

 ventrally at each foot, and there is no communication with the perigastric chamber. 

 The longer limb conveys the generative elements externally. The areolated tissue of 

 the foot receives the ova or sperms, and it is a development of the segmental organs. 

 The female in this group is much larger, he says, than the male. 



Kinberg (1865) made a step in advance in the classification of the Nereids by 

 placing the structure of the proboscis (his pharynx) on a proper footing. He termed the 

 distal region in extrusion the maxillary ring, and the proximal the basal ring. Moreover, 



1 'Arch. f. Naturges./ Bd. xvi, p. 294, 1850. 

 3 'Familien der Anneliden/ p. 125, 1851. 



3 And in this connection I have to remember the kindness and courtesy of Dr. Gray, Dr. Baird, 

 Dr. Grunther, Prof. Jeffrey Bell, and others. 



4 ' Philos. Tran?./ 1852, pp. 627—628. 



5 Ibid., 1858, p. 124. 



6 < Of vers. k. Yet.-Akad. Fork./ 1865, No. 2, p. 167. 



