260 MICRONEREIS. 



Lycastis, in which the dorsal division of the foot is rudimentary, being represented as a 

 rule by a spine and a few bristles. A recent contribution by Dr. R. Horst 1 on one of 

 Johnson's species (Lycastis hawaierisis) shows that the dorsal cirrus becomes greatly 

 developed. This form seemed to have been conveyed to the fresh-water pond of the 

 Botanical Gardens at Buitenzorg in transplanting mangrove trees. 



No example of Ceratocephale (a form with soft papilla in the proboscis) has yet been 

 found in British waters, yet it occurs on the opposite shores of the Atlantic (Canada), in 

 Sweden, and in Japan. The Japanese species, Ceratocephale osawai, Izuka, 2 is the 

 "Palolo" of their seas, occurring in swarms in October and November close to the new 

 and the full moon, and thus in four different periods each lasting a few days. It, like the 

 swarming Nereis Dumerilii of Britain, is much used as bait, and is captured at night with 

 nets, each boat having a lantern to attract the worms. It differs from the Atlantic and 

 Pacific "Palolos" not only in family, but in the fact that its posterior end is shed as a 

 useless product, the ova and sperms being discharged from the open posterior end of the 

 anterior region, which swims freely. Dr. H. C. Sorby 3 has found in the summer months 

 Heteronereids swimming very actively off the estuary of the Thames and elsewhere, and 

 then suddenly disappearing. 



SECTION I. 



NEREIDS WITHOUT PARAGNATHI IN THE PROBOSCIS, AND WITH 



BIRAMOUS FEET. 



1. Micronereis variegata, Claparecle. 4 Head without tentacles or palpi; peristomial 

 segment with feet and bristles. Bristles all homogomph with long slender tips. Length 

 4 — 6 mm. 



2. Leptonereis vaillanti, De St. Joseph. Head rounded, buccal segment passing 

 below, so that the tentacular cirri appear at its sides ; conspicuous glands in feet. Bristles 

 of more than one kind. Length 30 mm. 



Genus LVIII. — Micronereis, Claparede, 1863. 



Buccal segment bears feet and bristles. Proboscis muscular, only with maxillae. 



Foot deeply cleft, with a dorsal and a ventral cirrus. Bristles uniform throughout ; 

 homogomph. 



This genus, therefore, would naturally fall into the group devoid of paragnathi, and 

 is specially distinguished by having bristled feet on the buccal segment. 



1 ' Bullet. Dep. Agric. aux Indes Neerlandaises/ No. xxv, p. 1 (sep. copy). 



2 ' Journ. Coll. Sci. Imper. Univ. Tokyo/ vol. xvii, art. ii, pp. 1—37, 2 pis. 



3 ' Journ. Linn. Soc./ vol. xxix, p. 434, 1906. 



4 See a useful key to the British species by Major Elwes, ' Journ. M. B. A./ n.s., vol. viii, p. 357, 

 1909. 



