562 
BULLETIN OF THE BUREAU OF FISHERIES 
between Microgobius and Gobiosoma which generally become established when the 
fish reach a length of about 4.0 mm, remain essentially as described in the preceding 
paragraph (fig. 51). 
Specimens 7.5 mm long . — The general shape of the body, as well as the head and 
mouth remain very similar in Microgobius and Gobiosoma. The slightly larger eye 
in the first-mentioned genus, noticed in the very smallest larvae at hand, remains 
evident. The second dorsal and anal fins are quite fully developed and a fairly 
accurate fin-ray count is obtainable. In addition to the higher fin-ray count (second 
dorsal and anal each with about 16 or 17 rays) in Microgobius, it is evident now that 
the caudal peduncle also is shorter. The color markings in Microgobius remain 
largely as when they first appeared, except that no dark markings are present on the 
back in any of the specimens examined. The two rows of dark spots along either side 
of the base of the anal fin are more distinct and each spot is now horizontally slightly 
elongate (fig. 52). 
Figure 52 —Microgobiut sp. From a specimen 7.6 mm long. 
Specimens 10 mm long . — A difference in the shape of the body between specimens 
of Microgobius and Gobiosoma is plainly evident in examples about 10 mm long. 
In Microgobius the body remains nearly as strongly compressed as in smaller fry, but 
in Gobiosoma it has become notably more robust anteriorly and the head is broader with 
a wider interorbital space. Although the mouth remains about equally oblique in the 
representatives of each genus, it is evident now that the gape in Microgobius is 
somewhat larger, the maxillary reaching about below the anterior margin of the pupil, 
whereas it ends slightly in advance of this point in Gobiosoma. All the fins, exclusive 
of the first dorsal, are now quite fully developed. The ventral disk is long and slender. 
The caudal fin is shorter than the head and its margin remains straight to slightly 
concave. The spinous dorsal usually consists of four very slender spines, with two 
or three of the posterior ones still missing. Pigmentation has advanced only slightly. 
In addition to the pigment spots described in smaller fish, at least some specimens 
now have a few dark markings about the mouth, a few on the side of the head and an 
indication of a slight dark bar at the base of the caudal. Some specimens also have 
some black dots along the bases of the dorsal fins (fig. 53). 
