47 ° 
TUBE-BLADDERED GROUP. 
separate and of normal form; while in the skull the parietal bones are separated 
by the supraoccipital, all the opercular bones are present, and the pharyngeals are 
distinct, the upper ones being directed forwards, and three or four in number. As 
a family, the cyprinodonts are specially distinguished by the margin of the upper 
jaw being constituted solely by the premaxillse, and the enlargement of the third 
upper pharyngeal bone. Externally they may be readily distinguished from the 
carps by the head being scaled as well as the body, and they have no barbels. Both 
jaws are toothed, and the pharyngeals are also furnished with teeth, which are 
heart-shaped. There is no fatty fin, and the dorsal is situated in the hinder half 
of the body. The air-bladder is simple, and the false gills are wanting. Inhabiting 
either fresh, brackish, or salt water, these fish are distributed over the south of 
Europe, Africa, Asia, and America; some being purely carnivorous, while others 
feed on the organic substances to be found in mud. Most of the forms are 
viviparous; and the males, which are much inferior in size to the females, and, 
according to Dr. Gunther, probably the smallest living fishes, frequently have the 
anal fin specially modified to aid in the reproductive process. As a rule, the fins are 
relatively larger in the males than in the females, and there is likewise some 
difference in the coloration of the two sexes. In a fossil state, remains of the 
typical genus occur in the Miocene strata of the 
Continent, which have also yielded others re¬ 
ferred to an existing American genus; while 
the head of a species much larger than any now 
living has been described from the Plioeene of 
India, this specimen being figured in the accom¬ 
panying illustration in order to show the scales 
on the head so characteristic of the family. 
Cyprinodonts are represented by about a score 
of genera, which may be divided into two sub¬ 
families, according to the nature of the food. 
In the first of these, which includes the typical 
genus Cyprinodon, and has a distribution co¬ 
extensive with that of the family, all the forms 
are carnivorous or insectivorous, and are char¬ 
acterised by the firm union of the two branches 
of the lower jaw in front, and likewise by the shortness, or slight convolution 
of the intestines. On the other hand, in the second subfamily, which is exclusively 
restricted to Tropical America, the species seek their food in mud, and have the 
two branches of the lower jaw but loosely joined together, while the intestine is 
highly convoluted. It is in this group that the sexual differences are most strongly 
marked. 
HEAD OF A FOSSIL CYPRINODONT, WITH 
ONE OF THE SCALES ENLARGED. 
Double Eyes an example of the family we take a remarkable genus 
belonging to the first subfamily, represented by three species from 
Tropical America, one of which (Anableps tetropthalmus ) is shown in the accom¬ 
panying illustration. Having a broad and depressed head, with the region over the 
eyes much raised, the elongate body compressed in front and depressed behind, a 
protractile muzzle, and the cleft of the mouth horizontal and of moderate size, these 
