REPORT ON THE PELAGIC FISHES. 29 



long. 15° 16' W., small Pleuronectidae were obtained in the towing-net, the relation of 

 which to adult forms is at present likewise perfectly obscure. 



They (PI. I. fig. B) have a length of 6 and 7 mm. The notochord is distinct in its 

 whole course, with its diphycercal termination. The eyes are symmetrical ; no pigment is 

 to be seen on any part of the body except in three spots placed in a triangle opposite to 

 the end of the notochord. The fin-rays are perfectly developed, no part of the embryonic 

 fin-membrane remaining. The dorsal and anal portion pass uninterruptedly into the 

 rayed fringe surrounding the termination of the tail. Very peculiar is an exceedingly 

 long filamentous ray placed in front of the dorsal fin somewhat in advance of the eye. 

 Neither pectoral nor ventral fins can be distinguished, but this may be owing to the 

 condition of the specimens, which were mounted for microscopical examination imme- 

 diately after their capture. Also the configuration of the bones of the side of the head 

 is indistinct, but the mouth appears to have been of moderate width, and is armed with 

 a few tooth-like apophyses. 



Another larval Pleuronectoid, figured on PI. IV. fig. E, is possibly the young of a 

 Solea. It is only 5^ mm. long, and was obtained at the surface, off the mouth of the 

 Plate River on February 26, 1876. It was stained and mounted for the microscope, 

 scarcely more than the outlines being visible ; the posterior outlines of the head are 

 very indistinct. The specimen is not far advanced beyond the embryonic condition, and 

 its abdomen protrudes as a rounded sac. The tail tapers and is diphycercal ; eyes and 

 the small mouth symmetrical. Snout very short, with a parabolic outline ; eye small, 

 nearer to the angle of the mouth than to the upper profile. Fin -rays are developed and 

 differentiated only anteriorly on the back, the remainder of the fin showing a finely 

 striated appearance throughout its length, in its continuation round the end of the tail 

 to the vent. The two first fin-i'ays stand above the eye, are much elongate, nearly 

 3 mm. long, and are followed by about eight developed rays. Pectoral and ventral fins 

 apparently absent. 



In a young Pleuronectoid (PI. IV. fig. D), 13^ mm. long, obtained in the surface-net 

 on the passage from the Admiralty Islands to Japan, March 1875, the fins and rays are 

 much more developed. The body is whitish, semitransparent, like that of a Lepto- 

 cephalus, the eyes and mouth are symmetrical. The anterior profile of the snout is 

 parabolic ; the small eye is close to the anterior profile, above the angle of the narrow 

 mouth. Abdomen pendent and protruding. Pectoral well developed, on both sides, with 

 broad base ; a rayed fold of the integument, attached to the abdominal sac, represents 

 the ventral fin. The vertical fins are continuous, but the caudal projects as a distinct 

 portion and is composed of twelve rays. Dorsal rays about one hundred, anal seventy-four. 



This large number of fin-rays Avould seem to indicate that this fish is the young of 

 some species of Synaptura. 



