LARVAL AND POST-LARVAL FISHES—REGAN. 139 
and have such a wide range that the definite assignment of larvae to their species 1s 
very dithcult. This difficulty is increased by the fact that the head, owing to the 
relatively smaller size of the eye and mouth and the greater length of the snout, has a 
physiognomy quite unlike that of the adult fish. However, by counting the myotomes 
and fin-rays and taking into consideration the position of the fins, the size of the 
mouth, etc., it is possible to make determinations which may, in some cases, approximate 
to the truth. 
The general character of the development has already been described in dealing 
with Myctophum antarcticum. 
Myctophum benoiti, Cocco (PI. VI, figs. 1, 2). 
Several examples, from 4 to 7 mm. in total length, may belong to this species. 
They have much in common with the larvae described and figured by Holt and Byrne 
(Fisheries Ireland Sci. Invest. 1910, VI, p. 29, pl. I, fig. 8), from the Irish Atlantic 
slope under the name “ Scopelid larva, R 2,” but seem to be specifically distinct. They 
are distinguished by their rather deep form, conical snout, strong teeth, and by 
the distribution of the stellate pigment spots ; four large ones are present on each side, 
respectively at the origin of the dorsal and anal fins, below the adipose fin and above 
the end of the anal fin; usually there is a fifth on the side between the two last-named. 
There is also a spot on the back behind the head and a mid-ventral series of small spots 
from the end of the lower jaw to the origin of the anal fin. I count 12 or 13 dorsal 
and 17 or 18 anal rays and 37 myotomes. 
South Atlantic. Station 311. 35° 29'S., 50° 26’ W. 2 metres. April 22nd, 1913. 
Myctophum laternatum, Garm. (Pl. VI, fig. 7). 
A specimen 8 mm. long is probably of this species. It is moderately elongate ; the 
snout is short and the mouth is small, the maxillary extending to below the middle of 
the eye. The anal fin has 14 rays and commences below the posterior part of the 
dorsal, which has 11. The myotomes number 35. 
South Atlantic. Station 311. 35° 29'S., 50° 26’ W. 2 metres. April 22nd, 1913. 
Myctophum coccor, Cocco. 
An example 20 mm. long has the characters of the adult fish, except that the eye 
is relatively smaller, its diameter being less than the length of the snout. 
Station 86. Off Three Kings Islands. 3 metres. July 25th, 1911. . 
Diaphus sp. (Pl. V1, figs. 3, 4). 
Form rather deep; snout obtuse and mouth oblique. Length 4 to 5 mm. Dorsal 
and anal fins each with about 14 rays; about 35 myotomes. The distribution of the 
pigment is shown in the figures. 
Station 135. Spirits Bay, near North Cape, New Zealand. 3 metres. September 
Misty LOI: 
