52 EULALIA BILINEATA. 



rupted double line extends along the middle. When filled with ova, e. g. in May, they 

 are of a fine pea-green hue with the two dark-brownish lines. On the other hand, the 

 ripe males (July) are whitish-yellow from the contained sperms, the posterior region of 

 the body especially being enlarged. In spirit-preparations a dark speck is observed on 

 the dorsum at the base of each foot ; whilst in life a dark spot occurs on each side of the 

 segments ventrally. 



The typical foot somewhat resembles that in Eulalia trijnmctata, and it is doubtful if 

 the species could be distinguished readily by the outlines of the feet when mounted. The 

 bristles (Plate LXXVII, fig. 23 a and b) are also very similar, the only feature being the 

 presence in this species (E. bilineata) of a more distinctly spinous region at the enlarged 

 distal end of the shaft, the slightly longer bristles and their more evident curvature. 



Both dorsal and ventral cirri are pale and ovato-lanceolate. The ventral is not so 

 prominent as the tip of the setigerous process. 



Reproduction. — Both males and females are ripe in the summer months from May to 

 July, the females in this condition being pea-green, and the males whitish-yellow — 

 the posterior half of the body being much enlarged. The sperms (Plate LXVII, fig. 7) 

 are comparatively large, have a globular head and a long tail. Their vitality seems to be 

 considerable. 



Moreover the feet of the males have long simple bristles (Plate LXXVII, fig. 24) 

 dorsally in addition to the ordinary forms, so that an epitokous condition is present. 

 They also swim readily : even the separate fragments pass swiftly through the water with 

 a wriggling screw-motion. In the ripe forms the muscular walls of the body are thinner. 

 Habits. — A restless species — constantly pushing its snout here and there and throw- 

 ing its mobile body into various folds and loops. It is common in the tidal region, 

 lurking in crevices of the fissured rocks along with Spio, in cavities on the under surface 

 of stones, and under empty shells to which it adheres. It is slender and graceful, 

 moving in captivity about the vessel swiftly and with somewhat regular undulations. 



In his original description in 1840 Dr. Johnston omitted the short median tentacle, 

 but in the ' Catalogue of Worms in the British Museum ' he adds that Mr. Dyster 

 observed it. 



The Eulalia saxicola of De Quatrefages l appears to be most nearly related to this 

 form. 



Such species as the Eulalia gracilis of Verrill 2 approach this form in the closest 

 manner, and further examination may render separation unnecessary. 



The Eulalia quadrilineata of De St. Joseph 3 from Cape Coz is an allied species. 

 An Eulalia from deep water off St. Andrews Bay, which has only been seen in spirit, 

 differs from the foregoing species in its larger size, greater development of the dorsal 

 lamella, and the slightly broader tips of the bristles. The head is somewhat ovate, with 

 the long diameter antero-posterior, and with a pair of small black eyes situated near the 

 posterior border. The anterior end is small, and the body gently dilates from before 



1 < Annel./ ii, p. 119, 1865. 



2 ' Invert. Vineyard Sound, U.S. Comm. P. and F./ 1878. ? 



3 ' Ann. Sc. Nat./ 8 e ser., t. v, p. 327, pi. xviii, figs. 127—130, 1898. 



