72 Prof. M'lntosh's Notes from the 



cloiifjated outline tlian others, and one of tliese is figured by 

 Couch * as tlie " Bleunoid Fork-beard/' In this instance the 

 ventral fins scarcely reach the vent. 



2. On the Female Ileteronereid of Nereis pelagica, L. 



In a former note on the British Nereids f it was stated 

 that, though Ehlcrs had recorded a heteronereid female of 

 Nereis pclac/ica, only male hcteronereids had hitherto come 

 under examination at St. Andrews. This uncertainty has 

 now been removed by the occurrence from September to 

 February of the earlier stages formerly mentioned, and about 

 this period and somewhat later of the fully developed 

 heteronereid female. Indeed, it is possible that in some 

 localities the chauge may occur earlier, since two examples 

 of a female heteronereid, apparently of this species, were 

 procured by Mr. Gray iu October 1904 in the stomach of a 

 salmon at Berwick-on-Tweed. 



Before the heteronereid condition is developed, the female 

 Nereis pelagica is distinguished by the lustrous deep brownish 

 or bronzed colour formerly mentioned, and the size is fre- 

 quently larger than that of the male. As the ova develop 

 and di^tend the posterior region the latter assumes a some- 

 what pale hue and by-and-by also the body generally becomes 

 somewhat shorter and broader from contraction. The 

 change of colour does not at first much affect the general 

 as])ect, and no sign of alteration in the structure of the feet 

 is visible externally, but they are highly vascular — the 

 dorsal edge of each being connected with the body by a 

 reticulated bar of blood-vessels. The eggs at this stage 

 are dull reddish and minutely granular, and have none of 

 the large globules of a subsequent stage ; moreover, in the 

 lustrous brown condition of the adult they are more minute. 

 The eyes as yet show no perceptible change. 



The next stage is characterized by the lustrous pale 

 greenish condition of the body from the 20th foot backward, 

 whilst the brownish-olive hue remains iu front. The head 

 has a pale trifid mark between the eyes, the median spur going 

 forward. The eyes do not show marked alteration, but the 

 anterior dorsal cirri have a slight enlargement at the base. 



* Op. cit. pi. cLv. 

 t Ann. & Mag. Nat. Hist. ser. 7, vol. x. p. 256 (Sept. 1902). 



I 



