254 NEREIDS. 



be numbered the eight groups of paragnathi and utilized their presence or absence as 

 an aid in classification. Thus, to arrange them according as they occur on the 

 maxillary or the basilar ring, as Gravier 1 has done, they are as follows : 



Maxillary ring. Basal ring. 



Unpaired median dorsal group I. V. 



Lateral dorsal pair . . . . II. . VI. 



Unpaired median ventral group . . . III. . VII. 



Lateral ventral pair .... IV. . VIII. 



He made five families, or rather, as they might be termed, sub-families of the Nereids, 



according to the presence of these papillse and their nature, or their absence, using the 



structure of the feet, the bristles, and other features in separating the subordinate groups. 



De Quatrefages (1865) classified the Nereides according to the condition of the 



body, viz., those having one region or two, the uniramous or biramous nature of the feet, 



and the foliaceous condition of the latter. Since he included as separate genera the 



Heteronereids, the classification is now obsolete. In his characters of the genus 



Nereis he terms the palpi the external lateral antennas, and the tentacular cirri 



tentacles. The lobes of the feet are considered as branchiae. 



Malmgren (1867) arranged the genera according to the uniform or dissimilar feet 

 along the sides of the body, the characters of the bristles, and the structure of the 

 paragnathi. He made two great groups, according to the foliaceous or non-foliaceous 

 condition of the superior lamella of the dorsal lobe of the foot. Then again he subdivided 

 them into those having the feet uniformly constructed throughout, and those in which 

 the feet in the posterior region were transformed. His other characters rest on the 

 form of the dorsal lobe and the condition of the paragnathi. As the epitokous forms 

 are included in this arrangement, considerable changes are necessary. 



This author 2 has the credit of having subsequently discovered the relationships 

 between the Heteronereis-condition and the ordinary one in Nereis pelagica, in which 

 the male is Heteronereis grandifolia, and between Heteronereis fvcicola and Nereilepas 

 variabilis, (Erst., which he deemed equivalent to Nereis Dumerilii. He also showed that 

 examples of Nereis Dumerilii were either male or female, and that others with ova 

 assumed the Ijphinereis form. He was followed at no long interval by Ehlers, 

 Claparede, and others on this important question. 



Cosmorici (1880) described the segmental organs in N. bilineata as in pairs on 

 the posterior faces of the dissepiments in the middle region of the body. 3 



Following Malmgren, Ehlers 4 pointed out the relationship of Heteronereis to Nereis 

 and Nereilepas, taking especially Nereis Dumerilii with its conspicuous characters as an 

 example, and alluding to the analogous condition in the Syltids with their swimming 

 bristles. 



The same author (1868) characterizes the family Lycoridea, Savigny, Grube, as 

 having an elongated and distinctly segmented body. Head clearly differentiated with 



1 ( Nouv. Arch. Mus. Paris/ 4 e ser., t. iii, p. 151. 



3 'Zeitschr. f. wiss. Zool./ Bd. xix, p. 466; and in ' Arch. f. Naturges./ Bd. xxxv, p. 58, 1869. 



3 ' Thesis/ p. 113, pi. xxvi, fig. 14. 



4 ' Nachricht. d. k. Gesellsch. zu Gottingen/ pp. 209—217, 1867. 



