920 FISHES—A PHREDODERIDZ. 
lateral line; vent always anterior; its position varying with age, being behind the ven- 
trals in the young and jugular in the adult, a singular fact, first noted by Prof. 8. A. 
Forbes. A single species in this remarkable family is known. This inhabits the low- 
land waters, ditches and bayous of the Mississippi Valley and Atlantic coast. 
GENus 60. APHREDODERUS. Le Sueur. . 
Aphredoderus, LeSueur, Cuv. et VAL., Hist. Nat. des Poiss, ix, 1838, 329. 
Sternotremia, NELSON, Bull. Iils. Soc. Nat. Hist., i, 1876, 39. 
Asternotremia, Nelson, JORDAN, Bull. U. S. Nat. Mus., x, 1877, —. 
Aphrodedirus, COPE. Aphododerus, JORDAN, corrected orthography. 
Type, Aphredoderus gibbosus, LeSueur, = Scolopsis sayanus, Gilliams. 
Etymology, aphodos, excrement; dere, the neck or throat, from position of the vent. 
Characters of the genus included above. The body in the known species is rather 
short, compressed, thickened and bluntish forward ; the general color is olivaceous, and 
a dark bar is present below the eye and at the base of the caudal fin. 
The study of the position of the vent in this genus has developed some singular 
things. It becomes evident from the examination of a large series that the position of 
the vent is not a character of generic importance, as was supposed when the genus 
Sternotremia was proposed, nor is it apparently an individual or a sexual character as 
has since been suggested. . The observations of Professor Forbes, verified by myself, ap- 
pear to show that the position of the vent is dependent on the age of the fish. In the | 
adult, the vent is jugular, close behind the little projecting knob at the throat. In the 
youngest specimens examined, it is more or less behind the ventral fins. In specimens 
intermediate in size, its position is intermediate, the degree of advancement being pro- 
portionate to the size of the fish. 
Occasional irregularities occur, but the above rule holds so generally. that it cannot 
be merely accidental. From it, I infer that in the very young, the position of the vent 
will be found to be as usual in Percoid fiskes, as in the young Flounder the eyes 
are symmetrical, the aberrant characters being developed with age. 
This moving forward of the vent seems to be simply due to the lengthening of the 
horizontal part of the intestine or ‘‘ rectum” of the fish. Aphododerus sayanus is one of 
the most highly interesting of our fishes and a complete study of its em Ey CIey) would 
be very desirable. . 
A closely related family Hlassomatide, with a single known species Hlassoma zonatum 
occurs in the streams and ponds of Southern Illinois and may be found in Ohio. It is 
perhaps the smallest of all spinous fishes. In Hlassoma, the vent is normal in position 
and the ventral rays are in the normal number I, 5. The dorsal fin is rednced in size as 
in Aphredoderus. 
112. APHREDODERUS SAYANUS (Gilliams) Dekay. 
Pirate Perch. 
Scolopsis sayanus, GILLIAMS, Journ. Acad. Nat. Sci. Phila., iv, 182-, 81. 
Aphredoderus sayanus, DEKAay, New York Fauna, Fishes, 1842, 35.—BarirD, Ninth Smith- 
sonian Rept., 1855, 326.—GUNTHER, Cat. Fishes Brit. Mus., i, 271, and of authors 
generally. 
