DEVELOPMENT AND LIFE HISTORY OF SOME TELEOSTS 
561 
times in the length in Microgobius (with a range of 2.02 to 2.3) and 2.24 times in 
Gobiosoma (with a range of 2.13 to 2.33). Microgobius also has a slightly larger 
eye. However, the difference is so slight and the size of the eye changes so rapidly 
with growth that the difference cannot be shown easily in a table of measurements. 
Furthermore, the size of the eye in the delicate larvae of this size appears to have been 
affected by the strength of the preservative used which varied considerably with the 
different lots in the present collection. 
The first concrete difference observed between specimens of Microgobius and 
Gobiosoma are color markings which generally are fairly well developed at a length 
of 4.0 mm, frequently at 3.0 mm, and occasionally at a somewhat smaller size. Gobio- 
soma, as explained elsewhere (p. 555), has only a few dark markings on the ventral 
outline, consisting generally of about two elongate spots on the median ventral line 
under the head and on the chest, a larger spot or blotch at the vent and a few posterior 
to the vent, including one (situated at the last rays of the anal fin when that member 
becomes developed) that is notably larger than the others. Microgobius, on the other 
hand, has more numerous dark spots on the ventral outline and a double row of rather 
Figure 51 . — Microgobius sp. From a specimen 4.5 mm long. 
well outlined dots extending from the vent to near the end of the tail, or nearly to 
the base of the caudal fin when that member becomes developed. The dark spot at 
the vent typically forms a short black line lying parallel with the upper margin of the 
loosely attached hind gut. Occasionally the larvae of Microgobius, only a few 
millimeters long, have a few dark spots at the nape and two more or less definite rows 
of minute black dots on the dorsal surface of the caudal portion of the body (fig. 51). 
No markings of any kind have been noticed on the dorsal outline in the larvae of 
Gobiosoma. 
Specimens 5.0 mm long . — At a length of about 5.0 mm the second dorsal and 
anal fins usually are sufficiently developed (although some of the posterior rays 
generally are undifferentiated) to admit of a count accurate enough to establish the 
fact that these fins are too long for Gobiosoma which has only 11 or 12 rays in each 
fin. The slightly larger eye in Microgobius remains equally as evident at this size 
as in the smaller individuals previously described. Differences in color markings 
