OPHIODROMUS FLEXUOSUS. 119 



and tapering simple bristles arises. When fully developed the shaft (Plate LXXIX, 

 figs. 1, la, and 1 b) is longitudinally striated and has faint transverse touches, after the 

 manner of the ventral series, though much less distinct. The ventral division of the foot 

 presents a setigerous region, likewise carried outwards as a long tapering process (d) 

 enclosing the spine, and from the posterior surface of the base of which issues the 

 somewhat stiff fan of compound bristles (Plate LXXVIII, figs, la and 16). As usual 

 in such forms the anterior segments possess bristles with somewhat shorter terminal 

 processes, while the posterior (fig. 1 a) have their tips more elongated. Besides, in each 

 foot the tips vary in length, the shorter being met with superiorly and inferiorly. The 

 claw at the tip of the terminal division is somewhat indistinct, from the blocking of its 

 outline by a process beneath. The serratures of the sabre are very fine and scarcely 

 distinguishable towards the tip. The shaft of the bristle is obliquely striated towards 

 the articulation, longitudinally throughout the rest of its extent, except at the pale base, 

 and marked by a close series of transverse strise. 



In structure these bristles differ from allied British forms, e. g. Gastalia fusca and 

 Gastalia punctata, each of which has compound bristles, and the peculiarly clawed serrated 

 terminal process. Thus in the first-mentioned the larger size, the structure of the shaft, 

 and the coarser serratures on the terminal process, distinguish it from Gastalia punctata, 

 while the latter again has a much broader and proportionally larger terminal blade with 

 coarser serratures and a better defined claw than in Ophiodromus, and though the shaft 

 of the bristle more closely resembles it than that of Gastalia fusca yet it characteristically 

 differs therefrom. The distinctions between Ophiodromus and the Pariboea and Podarke 

 of Ehlers are not so clear ; indeed, the latter appears to be allied in the closest manner, if 

 it is not identical. Unfortunately Ehlers does not figure the bristles on a large scale, so 

 that their minute structure is uncertain. From the inferior border of the foot arises the 

 inferior cirrus (e) which tapers gently towards the tip, and is shorter than the dorsal. 



Reproduction. — A large number of orange-coloured ova were emitted from a ruptured 

 female in August, and those procured by Canon Norman off Bergen, Norway, in July 

 showed the same feature. The ova are comparatively large. 



Claparede (1870) states that the ova of the Mediterranean examples were of a 

 greenish-brown and Oil mm. in diameter. 



Habits.— Few annelids display so much activity and irritability. If the head is 

 touched it darts vigorously backward, and if the tail is irritated it rushes as rapidly 

 forward — with a wriggling sinuous motion. It is very sensitive to admixture of the sea- 

 water with fresh. Thus, when conveying living specimens from North Uist in 1865 for 

 a coloured drawing, the jar was replenished with sea- water at Dunvegan. Unfortunately 

 the mists and rains obscured the surroundings of the creek — which had several streams of 

 fresh water debouching into it, and it was mortifying to see the fine examples become 

 pale and die in a few seconds after the dilute sea- water touched them. In other Hesio- 

 nidas the changes in colour have been mentioned by several observers. Thus Professor 

 Haswell l noticed that specimens of Halla parthenopeia changed from bright yellow to 

 deep purple when placed in spirit. Mr. Crossland tells me that in Halla (Aglaura) fulgida, 

 Sav., of the Red Sea : " The worm becomes dark when exposed to the air, whilst fresh 



1 ' Proc. Linn. Soc. N.S.W./ x, p. 752. (1886.) 



