310 NEREIS DUMERILIL 



So far as can be observed the Nereis Beaucondrayi of Audouin and Edwards 1 comes 

 nearest this species. 



The Lycoris Dumerilii of H. Rathke 2 (1837) probably refers to this form, though the 

 figures are imperfect. 



The Nereis agilis of Keferstein 3 (1862) appears to come nearest this species, though 

 the figures show certain differences, probably due to the artist. 



For similar reasons to those already mentioned under Nereis Schmardaei it is 

 unnecessary to retain Malmgren's genus Leontis (1867) for this form. 



The same author 4 pointed out the relationship of Ip/iiuereis fucicola, OErsted 

 (Heteronereis fucicola, Auct.), with N. Dumerilii, viz., a sexual stage in its life-history. 



Ehlers (1868) gives a careful description of this form both in its atokous and 

 epitokous conditions, and in the different sexes. In the epitokous male he describes the 

 cirri of the first four feet as enlarged at the base, the change of the feet occurring on the 

 sixteenth, in the female on the twenty-first. The cirri in the female are simple ; those 

 of the male furnished with papillae or warts. 



Claparecle (1868) describes Heteronereis Malmgreni, a pelagic Nereid from the surface 

 of those currents which occur between Capri and Sorrento. The tissues are most delicate 

 and the agility great in both males and females. The species is probably identical with 

 the present. He gives fifteen segments to the anterior region (his thoracic) in the 

 male, and twenty-two in the female. He draws attention to the ventral direction of the 

 palpi, which are thus invisible from the dorsum, and notes that the form differs from 

 II. CErstedi, De Quatrefages, from Palermo, in so far as the median tentacle in the latter 

 is biarticulate and the form of the foot different. Further investigation, however, is 

 needed. 



Moquin-Tandon 5 found at Marseilles a hermaphrodite Nereid, which he termed Nereis 

 massilie?isis, with spermatozoa and ova floating freely in the body-cavity. This apparently 

 is the hermaphrodite form of N. Dumerilii, which occurs in a membranous tube amongst 

 Ulvas. He also found two under the same circumstances loaded with eggs only. 



Claparede (1870) cites this form as one of the most puzzling of the group, for whilst 

 forms of 13 — 14 mm. may be ripe, others of 50 — 60 mm. in length give no trace of sexual 

 maturity. Again, at different epochs of their existence the males show sperms of 

 totally different form. In his elaborate study of the Nereid and Heteronereid stages of 

 this species he shows that there are five kinds of bristles in the Nereid, whereas in the 

 pelagic Heteronereid there are but three, viz., the awn-like homogomph, the falcigerous 

 heterogomph, and the sabre-like heterogomph. The falcigerous homogomph only appears 

 at the twentieth segment. He has met with individuals possessing all the characters 

 of Heteronereicls, yet the bristles were Nereid. The presence of peritoneal pigment 

 (purple, etc.), and the homogomph bristle in the inferior fascicle of the dorsal division of 



1 ' Annel./ p. 192, pi. iv, figs. 1—7, 1834. 



2 ' Fauna der Koym./ p. 419, Tab. vii, figs. 3, 16, and 17, 1837. 



3 ( Zeitschr. f. wiss. Zool./ Bd. xii, p. 97, Tat*, viii, figs. 8—11, 1862. 

 i < Annul. Polycli./ p. 59, April, 1867. 



5 'Compt. Rend./ April 12th, 1869, t. lxviii, p. 869; 'Ann. So. Nat./ 1869, p. 134; and < Ann. 

 Nat. Hist./ 4th ser., vol. iv, p. 73, 1869. 



