GTJimiEIt — FRESH- WATER FISHES* 
225 
distinguished from the females by smaller size, more orna- 
mental colours, greater development of the fins, and fre- 
quently by the modification of the anterior anal rays into 
nn intromittent organ. 
As regards Trinidad, only one species was known to me 
to occur in the island, viz. 4 the Strdbleps tetrophthalmus , 
distinguished by the peculiar structure of its eye, by which 
it is asserted to be enabled to see simultaneously above and 
within the water, when it swims with a part of the head 
raised above the surface. Specimens of this fish were col- 
lected by Mr. Cutter during a short visit to the Island. 
Mr. R. J. Lechmere Guppy kindly presented to the Bri- 
tish Museum two other species of which descriptions are 
added here, and I have no doubt that continued researches 
will reveal many other species of this singular group. 
Rivulus micropus (Steindachner). 
The length of the head is one-fourth of the total (without 
caudal), the height of the body two-elevenths. Snout round- 
ed, with the jaws equal in length, somewhat shorter than 
the eye, which is one-third or two-sevenths of the length 
of the head. Mandible as long as the eye. Interorbital 
space quite fiat, its width being half the length of the head. 
Dorsal fin situated far backward, opposite to the posterior 
third of the anal, and its distance from the gill-opening 
equals double the length of the head. Yentral fins very 
small, not much longer than the eye, and reaching the 
vent. Pectoral terminating at a great distance from the 
ventral. Light brownish body with a longitudinal series 
of dark brown dots, two of the series being very conspi- 
cuous. Vertical fins striolated with blackish brown. Gene- 
