DEVELOPMENT AND LIFE-HISTORIES OF TELEOSTEAN FISHES. 865 
last stage, and a pale process or papilla indicates the presence of the ventral fins. The 
next stage to be noticed (about 5 mm. in length) shows a more regular fusiform outline, 
and from the increase of pigment along the ventral surface it is considerably darker than 
the dorsal. By the widening of the cheeks the eyes have become more oblique, so that 
they are largely seen from the dorsum, whereas in the earlier stage they were more in har- 
mony with the usual piscine type. The forward growth of the premaxillary region, and 
the increased arch of the mandible, greatly alter the facial aspect. The ventrals appear 
as a pair of short fins below and in front of the pectorals. From the marginal fin the 
anal is differentiated inferiorly, and is separated by an interval from the caudal. The 
fin-rays are much more distinct in this lower fin than in the dorsal. The development of 
the hypurals has pushed the tip of the notochord upward, but it is still surrounded by 
the embryonic marginal fin. The inferior caudal rays far exceed it in length, and they 
spring from a vertical hypural edge. The shape of the tail is conical, broad at the base, 
and narrow at the tip. The opercular margin does not yet show spines. 
When 1 or 2 mm. longer, the arrangement of the pigment is unaltered, the ventral 
surface and posterior region of the body being tinted somewhat deeply by stellate 
pigment-corpuscles, while the dorsum is less uniformly coloured. The body behind the 
abdomen is thicker, so that when seen laterally the fish is fusiform, though, viewed from 
the dorsum, the head and abdomen are still disproportionately broad. The pectorals and 
ventrals are larger, the former showing blackish pigment-specks on the fleshy basal region, 
and a few dark radu on the fan-shaped distal region. The under surface of the ventrals 
also exhibits dark streaks between the rays, and they are considerably shorter than the 
pectorals. In shape both pairs of fins approach those of the adult. The first dorsal is 
merely indicated by a few short processes. The pale second dorsal fin (the embryonic 
fin having disappeared) begins behind the middle of the back, and terminates a short dis- 
tance in front of the caudal fin. From the anus the anal fin extends to a point below, and 
somewhat beyond the dorsal above, as shown by an imaginary vertical line. Between 
the rays very evident dark pigment-streaks occur, a feature in consonance with the 
development of pigment on the ventral surface. The tip of the embryonic tail has now 
coalesced with the upper lobe of the permanent caudal, and the latter is somewhat less 
conical as well as broader at its termination. In some of the more advanced specimens 
at this stage the opercular armature is present as a straight spine, with a spur—coming off 
nearly at right angles—toward the tip. 
When the length of 9 mm. has been attained, the body is still stouter behind the 
abdomen, the ventral fins have gained greatly on the pectorals, so that though they arise 
considerably in front of them, their tips are nearly in a line with the extremities of the 
former. The fan-like pectorals have much stiffer rays, arising from the semicircular 
base. The opercular spines stand out on a long process, and their tips slightly incline 
towards each other, the margin between them being semicircular. The first dorsal is now 
distinct, and the anterior rays of the second dorsal are longer than the others. 
When 10 mm. long, the characters of the adult are more evident, the telescopic mouth 
VOL. XXXV. PART III. (NO. 19). 68 
