944 The American Naturalist. [November, 
identify the species with his A. erebennus in The Fishes of North and 
Middle America, 1896, p. 139. From Jordan’s descriptions it is evi- 
dent that the A. prosthistius is nearer to the A. natalis than to the A. 
erebennus. The spines are not elongated as in the former, nor is the 
head long and narrowed forward, but it is short and wide; it enters 
the length (without caudal) 33 times and not four times. The mouth 
is relatively wider in the A. prosthistius, being .66 of the head-length, 
and not .5 of it asin A. erebennus. The inferior barbels are white in 
the former, while one may suppose they are black in the A. erebennus 
from Jordan’s description. The supraoccipital spine is widely separa- 
ted from the dorsal spine. In the specimens from Winslow the anal 
fin is relatively longer than in those from Batstow; in the former it 
enters the length (without caudal fin) very little over three times (3.2), 
while in the latter it enters from 3.5 times in one, to 3.66 in two, and 
3.85 in another. The length of the anal rays is .66 of that of the head 
in the Winslow specimens, and .5 of the head in the Batstow speci- 
mens. The latter are of larger size—E. D. Corr. 
On the Mud Minnow (Umbra pygmaea) as an air breather. 
—In the autumn of 1895, I tried to keep a few fishes alive in a small 
aquarium, viz., a glass jar holding about a gallon. This was filled with 
well water and some water plants placed in it which grew well. Vari- 
ous fish were placed in it from time to time but all without exception 
died in less than six hours except a Mud Minnow (Umbra pygmea) 
This came to the top at frequent intervals, on each occasion emitting 
bubbles of air and presumably gulping more down, making considerable 
noise in so doing. On being placed in well aerated water six weeks or 
more later, this habit ceased. 
The other fishes which were placed in the jar, Catfishes, Minnows, 
Sunfish, and Suckers would come at once to the top gasping for air, 
and died in an hour or two. 
I have placed other of these fish— Umbra pygmea, in well water and 
they acted the same way, coming to the top at frequent intervals and 
“bubbling ” each time. 
I have never found any of these fish dead in dried up pools, though 
I have carefully looked for them, presumably their ability to use air 
for respiration saves them.—C, 5. BRIMLEY. 
The Peritoneal Epithelium in Amphibia.—In a recent study 
of the peritoneal ephithelium in Amphibia the following points were 
noted. The species examined were Necturus maculatus, Amblystoma 
punctatum, Desmognathus fusea and Diemyctylus viridescens. All the 
