STRUCTURE OF THE CHONDRACANTHUS LOPHII. 75 



seen the embryoes lying in the sea-water still invested by the inner membrane of 

 the ovmn When the embryo finally escapes from the ovum, its shape, structure, 

 and appendages may be more clearly examined. The hirva is oval in shape, the 

 broader end being anterior. Length about iggth of ^^ inch. Dorsal surface some- 

 what convex. A pair of dark-coloured spots is seen at the anterior end. At 

 the posterior a couple of fine hairs projects backwards. An aggregated mass of 

 refracting globules, probably the remains of the yelk, lies in the centre of the 

 body in what may be supposed to be the intestine. 



A series of appendages projects beyond the sides of the larva. The anterior 

 pair, evidently antennae, are three-jointed, the terminal segment possessing two 

 hairs projecting from its free end. Behind the antennge, and distinctly arising 

 from the ventral aspect, are two pairs of swimming limbs. Each limb consists 

 of a basal and two terminal segments, one in front of the other. Each terminal 

 segment is furnished with hairs ; the anterior possesses two at its outer end, the 

 posterior has only one at its outer extremity, but in addition is furnished with 

 three along its anterior margin, each arising from a papilla-like projection. 

 Distinct muscular fibres, transversely striped, were seen in the body of the larva, 

 evidently connected to the basal segment of the limbs. Of mouth and anus we 

 saw no indications. The further development of the larva we had no opportunity 

 of tracing. 



PLATE III. — Explanation of Figures. 



Fig. I. Lateral view of Chondracanthus Lophii. The constriction t, separating the cephalic u, and 

 thoracic parts, the pair of antennae, a, at the anterior part of the head, and the number and 

 direction of the dorsal and lateral processes, are represented. The two spirally twisted 

 strings of ova project from the posterior part of the animal. The thoracic feet are indicated 

 at dd. 



Fig. 2. Ventral aspect — a, antenna; 6, hook; c, foot-jaws ; dd, thoracic feet; ee, ventral mesial 

 processes ; /, posterior end of alimentary canal ; g, abdomen ; h, cement organ. 



Fig. 3. Highly magnified view of the distal segment of one of the antennse. The continuity of the 

 parenchymatous substance of the hairs with that in the interior of the antenna itself is re- 

 presented. 



Fig. 4. Left hook organ — i, terminal hook; k, basal portion; I, frame. In A, tlie ventral aspect, 

 in B, the outer aspect is represented. 



Fig. 5. Ventral aspect of cephalic portion. The relations of the antennse a, hooks 6, mouth s, 

 foot-jaws c, and the origin of the first pair of thoracic feet d, are exhibited. Various muscular 

 bands for the foot- jaws, and portions of the longitudinal muscles are seen. 



Fig. 6. Enlarged view of foot-jaws of left side. C 1st, D 2d, E Zd foot-jaw. 



Fig. 7. Alimentary canal, with its lateral coeca and small terminal cul-de-sac. The muscular fibres 

 in its wall are represented. 



Fig. 8. Abdominal portion — m, proximal segment, with its somewhat bivalve-like shape ; n, distal 

 segment, bearing hair-like papillae ; o, ova-strings ; r, villus-like projection for attachment 

 of male. 



VOL. XXIII. PART I. X 



