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On Lepto nereis glauca Clpde., and the 

 Genus Leptonereis Kinberg. 



By 



L. N. G. Ramsay, M.A,, B.Sc, 



Carnegie Research /Scholar, Christ's CuUcge, Camhridge. 



AYith Plate 1 in tlie Text. 



INTRODUCTORY. 



In February of this year Mr. J. H. Orton collected a number of small 

 nereids on the piles of a wharf at the Great Western Docks at Millbay, 

 Plymouth. These he kindly handed over to me for identification, and, 

 along with other material collected at Plymouth in March, they form the 

 basis of this paper. 



These nereids proved to be none other than the little-known Leptonereis 

 glauca of Claparede, of which the only specimen hitherto recorded from 

 the shores of this country was found by Major E. V. Elwes at Oddicombe 

 (8, p. 351) some years ago. 



Claparede (3, p. 90) described the species from specimens obtained 

 by him at Naples about 1870. He gives a good description and figures, 

 but no particulars as to its numbers or habitat. It was next met with by 

 de St. Joseph, who found it commonly in dredgings at all depths on the 

 coasts of Dinard (6, p. 246) in 1888. This authority described his specimens 

 as a distinct species, naming it L. vaillanti. (I shall show later that the 

 two are identical.) He observed also the male and female heteronereids, 

 of which he gave excellent and detailed descriptions, with a number of 

 figures. 



Thenceforward, L. glauca was not met with so far as has been recorded, 

 until 1909, when Major Elwes found his specimen, a male heteronereid, 

 at Oddicombe. 



In 1878, however, Langerhans (5, p. 279) had described under the name 

 of Leonnates ^yusillus another small species of nereid which, as I hope to 

 show, is very closely related to, if not identical with, the one under 

 consideration. This species he found at Madeira, and he observed in 

 an aquarium the change to the heteronereid form in both sexes. 



