On a Specimen of Leptocephalus Morrisii.-During the first week of June of the present year, a specimen of Leptocephalus was brought to the Laboratory by a boy, who had found it under a stone on the shore, in a small cove in front of the building. The beach in this cove consists of broken fragments of limestone. The specimen was alive when brought up, and was preserved in formaldehyde. When I examined it a few weeks later it was entire and in excellent condition, and retained its transparency to a considerable degree in the preserving liquid. The specimen is 11.25 cm. long (4|in.); the greatest dorso-ventral breadth of the body, a little behind the anus, is 7 mm.; the breadth in the same direction at the back of the head is 5 mm. The dorsal line rises slightly behind the head. From the tip of the lower jaw to the anus the distance is 5.25 cm., from the tip of the snout to the commencement of the dorsal fin is 3.6 cm. Thus the point at which the dorsal fin commences is nearer to the anus than to the pectoral fin, although, in the fully developed conger, the dorsal fin extends forwards to a point in front of the posterior extremity of the pectorals. In this respect the larval form more resembles the adult common eel (Anguilla) than its own parent. The greatest lateral thickness of the body is just behind the head, and does not exceed 2 mm. Behind the anus it is narrower still. The head, however, is not much compressed laterally, but is rather broad, and flat on the dorsal surface. The length of the head is 8 mm., measured from the tip of the snout to the gill opening; its breadth is 3 mm.; its vertical height at the level of the eyes, 4 mm. In characters the head resembles that of the conger very closely. The eyes are large, the exposed front being silvery, except along the dorsal edge, where there is a streak of black pigment. The anterior tubular nostrils and the posterior open ones are present, as in the conger, and the gill opening is a reduced slit in front of the base of the pectoral, as in the latter. The upper jaw is a little longer than the lower, and the angle of the mouth is below the middle of the eye. No bones can be seen in the interior of the body by this examination of the entire animal without further