556 
BULLETIN OF THE BUREAU OF FISHERIES 
without evident rays. The caudal fin seems to have a nearly straight to a some- 
what concave posterior margin. In life the body remains highly transparent and 
the fish are almost invisible when caught in a net, except for the dark eyes. Pig- 
mentation on the body consists of two short dark lines situated on the median ventral 
line, the anterior one being under the posterior part of the head and the second one 
on the chest; a dark chromatopliore appears just in advance of the vent; and usually 
a series of indefinite dark markings extends from the origin of the anal to the base of 
the caudal, the last spot of the series being on the base of the lower caudal rays and 
generally slightly vertically elongate. These markings are different from those in 
related species of gobies occurring locally and serve as a recognition mark (fig. 45). 
Specimens 10 mm long. — The two local species of Gobiosoma are rather defi- 
nitely separable at a length of 10 mm. In both species the body has become more 
robust since a length of about 7.5 mm was attained and generally it is somewhat 
rounded anteriorly. The greatest depth of the body in bosci is contained in the length 
to the base of the caudal about 5.3 times, whereas ginsburgi generally is more slender, 
the depth being contained in the length about 6 times. In bosci the head is nearly 
as broad as deep, the eyes have become slightly superior, the snout is comparatively 
round and blunt, and the mouth is moderately oblique and terminal. In ginsburgi 
the development in all these respects is rather less pronounced. The ventral fins are 
quite fully developed as a sucking disk in both species (reaching its greatest develop- 
ment in bosci at this size and becoming proportionately shorter later in life), and the 
first dorsal is present, although the spines are very weak and slender. The margin of 
the caudal fin remains straight to slightly concave. Variation in the progress of pig- 
mentation is evident among specimens of the same species. However, the develop- 
ment generally is further advanced in bosci than in ginsburgi. In the latter no general 
pigmentation has taken place and the markings remain virtually as described for the 
7.5-mm fish. The posterior one of the two short dark lines on the median line of the 
chest is now situated at the base of the ventral disk. The dark markings along the 
base of the anal and on the ventral outline behind the anal clearly are short hyphen- 
shaped lines when viewed ventrally and are rather more distinct than in smaller fish. 
In the most profusely pigmented individuals of bosci indefinite cross bars are present 
on the upper part of the sides and back. Also, an oblique bar reaches from the eye to 
the mouth and another bar occupies the base of the caudal fin (fig. 46; based on a 
rather unusually well developed specimen for its size). 
A difference among specimens in the robustness of the body is present, as already 
shown. That the slender individuals generally are referable to ginsburgi is evident 
