324 NEREIS DIVERSICOLOR. 



concentrated by the addition of potassium chloride, and then returning them to ordinary 

 sea-water. 



In the British Museum specimens of this species from Bexhill and various parts 

 of the southern coast are labelled Nereis finibrlata, whilst others which bear the title 

 N divers loolor pertain to N. cidtrifera, N. pelagica, and AUtta virens. 



The Nereis falgens {versicolor) of Dalyell has been placed under this head with some 

 doubt. The figure might pass for the reddish-brown female of N. pelagica. 



This species is largely used for bait in the Channel Islands. Mr. Punnett also found 

 that at Gosport it was frequently employed for the capture of pollack. 



In his original account of this Nereid, 0. F. Miiller (1800) enters into a disquisition 

 as to the history of this " sea scolopendra," as such forms were termed by Aristotle, and 

 its connection with the " Rodat." 



The Nereis Beaacondrcuji of Aud. & Edw. and Keferstein x seems to come near this 

 form. 



Max Schultze in 1856 refers to the occurrence of the young in the body-cavity of the 

 mother, but so far as observations in this country go this has not been corroborated. He 

 seems to have considered that Koch's statements in regard to Marphysa sanguined were 

 literally true. 



Malmgren (1867) constituted the genus Hediste for this species, founding the distinc- 

 tion chiefly on the trifid nature of the superior division of the foot, but it seems unnecessary 

 to multiply genera on this basis. 



Schroder 2 (1886) gave a general account of this species structurally and otherwise, 

 and added a note in regard to its reproduction. His observations were made at Kiel. 



Mendthal (1889) thought the species was hermaphrodite, the ova being developed 

 at the bases of the feet, whilst the sperms occurred in the dorsal region external to the 

 longitudinal muscles. This has not been corroborated at St. Andrews. Like Schroder 

 he also found Gregarinae in the gut, and the early stages in the muscles. He also refers 

 to the respiratory function of the lobes of the feet. 



An interesting account of the " swarming " and development of Nereis japonica, 3 n. sp., 

 is given by Akira Izuka, who, while admitting close resemblances between it and Nereis 

 diversicolor, bases his distinction on the fact that the paragnathi in the Japanese form in 

 VII and VIII are arranged in a continuous row, whilst in N. diversicolor they are in the 

 form of three or four irregular rows, that the falcate bristles of the former are larger than 

 those of the latter, that the eyes have lenses in the Japanese, and that the breeding habits 

 of the latter differ from those of Nereis diversicolor. After a perusal of the description in 

 all its details, however, the very close resemblance of the two forms is apparent, and 

 though the " swarming" of N. diversicolor has not yet been observed in Scottish waters, 

 that and other slight divergences may be due to environment, and especially to tempera- 

 ture and food. It has to be remembered that some forms, e. g., Eunereis longissima, may 

 or may not have paragnathi, so that future investigations may show that changes of the 

 nature indicated by Izuka may not have the importance claimed for them. 



* 'Zeitsclir. f. wiss. Zool./ Bd. xii, 1862, p. 94, Taf. viii, figs. 1-6, and 12, 1862. 

 ' Anat. histol. Untersuch. von N. diversicolor, Rathenow/ 1886, 1 plate. 

 ' Aimot. Zool. Japon./ vol. vi, part 4, 1908. 



