1873.] MR. R. COLLETT ON CERTAIN GOBIOID FISHES. 333 



males. Although the total length is almost the same as in many of 

 the mature males (36-37 millims., in a single specimen 39 millims.), 

 their body is so slender and their weight so inconsiderable, that two 

 full-grown females, with the ovaries filled with ripe eggs, were not 

 able to weigh down one large full-grown male. The head is 

 pointed, with short jaws, which are straight and perfectly toothless, 

 and are wanting the males' prominent projection on the intermaxillary 

 bone. The first dorsal and the ventral fins are rudimentary (at a 

 superficial glance they appear to be entirely wanting) ; the pectoral 

 fins are certainly developed, but very short. The ovaries project far 

 behind the vent on each side of the anal fin. 



The young females, with a total length of 30-33 millims., and 

 with the ovaries filled with unripe eggs, have the body very slender 

 and pointed : as in the old female the jaws are toothless, the first 

 dorsal and the ventral fins apparently wanting. 



The young during growth. — The few young with a total length 

 of about 25 millims. that have been at my disposal have all been 

 males. This is shown by the first traces of teeth, by the want 

 of the long ovaries, as well as by the presence of all the fins ; cer- 

 tainly the first dorsal and the ventrals are short, but never wanting 

 or even rudimentary. These fins may already be seen in the young 

 with a total length of 21 millims., the smallest specimen I have 

 found ; in this one, however, there was not yet any trace of the 

 pectorals. 



It may therefore be supposed that in the males the first dorsal 

 and the ventral fins spring forth at a very early age, whilst the 

 females never have these fins developed ; the pectorals, on the other 

 hand, are present in both sexes (although in the female in a less- 

 developed state), but are always late in appearance. 



As compared with Latr. pellucidus, the difference in the exterior 

 between the sexes in the present species appears in several wavs 

 already at a very early period, whilst this difference in Latr. pellu- 

 cidus, as stated above, only becomes apparent in mature specimens. 



The construction of the body is thin and elongated, very com- 

 pressed, and does not, as is the case in Latr. pellucidus, practically 

 increase in plumpness in the spawning-season. 



In a full-grown specimen, ready for spawning, with a total length 

 of 46 millims. (caudal included), the length of the head is about 

 10 millims, and is contained A\ times in the total length. The 

 greatest height (5| millims.) continues almost unaltered from the 

 occiput to about a head's length from the caudal fin, and is con- 

 tained 8 1 times in the total. The vent, on the posterior margin of 

 which there is a small papilla, is situated halfway between the snout 

 and the root of the caudal, and in some individuals projects in the 

 form of a short tube. 



In the female, which, as stated above, is considerably smaller 

 than the male, the head is somewhat more pointed. In a specimen 

 with the eggs ripe the head is contained about 5 times or a little 

 more in the total length. 



The diameter of the eye is one fourth of the length of the head. 



