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388 HARRIS HAWTHORNE WILDER ON 
groups, which are partially or wholly subterranean in their habits and thus modified in 
various degrees to conform to this environment. Proteus is an inhabitant of certain 
caves in Austria, and shows, among other troglodytic characters, reduction of eyes, loss of 
pigment, and a pronounced attenuation of body and limb, the latter combined with a loss 
of toes. These aberrant characteristics are still more marked in the recently discovered 
Typhlomolge, which occurs in a subterranean river in the state of Texas. The third and 
last member of the group, Necturus, occurs in the Great Lakes and other open waters, 
and, corresponding to its freer life, shows the least modification. It remains by day 
beneath stones or in subterranean burrows constructed by itself in the mud, and becomes 
active at night, swimming through the water in search of prey. Its body and legs are 
robust, and do not show the slender proportions seen in Proteus and Typhlomolge. Its 
eyes, though small, are functional, and it is well pigmented, especially above. It is thus 
at the same time a representative of the lowest group of Urodeles, and one not extremely 
modified. 
The genus Necturus is exclusively North American and includes but one common 
species, V. maculatus Raf., although the series of synonyms, as well as some variability of 
marking, have combined to give the general impression that there is a large number. 
Aside from NV. maculatus Raf., Cope enumerates a second species, V. punctatus 
Gibbes. of rare occurrence and found only in the waters of North and South Carolina. 
Necturus maculatus, the subject of this memoir, is a widely distributed form and 
occurs in abundance in the Great Lakes and their tributaries, and throughout the entire 
Mississippi valley, as well as in many of the river systems of the Atlantic slope, and those 
flowing into the Gulf of Mexico. Its abundance and extensive distribution have led the 
United States governinent to conduct experiments relative to its introduction as a “ food 
fish,” thus far with satisfactory results. In form and appearance it is similar to that of a 
larval salamandrid, and is subcylindrical, body slightly and head markedly depressed, 
with three large and bushy external gills upon each side, having two gill slits between 
them, and with four decidedly robust legs, each with four toes. The tail, which does not 
exceed half the length of the body, is compressed and surrounded dorsally, caudally, and 
ventrally by a caudal fin, rounded in outline at the tip. Sexually mature adults seem to 
be fairly constant in size, varying in total length between about 27 cm, and 34 cm. 
The color markings of the integument are due to scattered pigment cells, the varia- 
tions in the frequency and size of which result in the formation of all possible shades 
between no color at all and dense black spots. As these cells are very large, and in most 
places evident to the unaided eye, the principle is seen upon close inspection to be similar 
to that of a modern half tone illustration, which a careful scrutiny resolves into a series of 
black dots, although in the latter case the darker shades are due to increased size, and in 
