182: The American Naturalist. (February, | 
by Mr. R. T. Günther during last winter, the Limnocnida tangany- 
isie, a fresh water jelly-fish from Lake Tanganyika. Individuals of 
three kinds are described by Mr. Giinther, viz.: males, females, and 
asexual individuals which produce crops of buds on the manubrium 
While differing from Limnocodium in most respects, Limnocnida 
agrees with it in the minute structure of the marginal sense organs, 
- According to Mr. Lankester no light is thrown by Limnocnida on the 
problem of the life history of Limnocodium. (Nature, Dee. 7, 1893.) _ 
The American freshwater hydroid Microhydra ryderii Potts, is sup 
posed to be a near ally Limnocodium. a 
Description of a New Genus and Species of Arvicoline 
Rodent from the United States, Rhoads, Gen. et. sp. 20% — 
(Lake Kichelos, Kittitas County, Washington.) —AULACoMYS ARVI 
COLOIDES.— Diagnostic Characters—Skull large, massive, angular; 
malars parallel. Superior incisors long and slender (about 
equalling length of nasals), projecting anteriorly, strongly recurved 
and with flattened faces. A narrow, longitudinal sulcus equally 
divides the anterior face of each superior incisor, this groove, slightly 
magnified, showing a clear-cut, well-defined channel. To the naket 
eye this channel can be detected only on closest scrutiny. First lone 
molar with six angles on each side, two isolated triangles oD the outer, 
and three isolated triangles on the inner side. On the inner side ws 
are made up: 1, an inner posterior angle or shoulder of the anteriot 
loop; 2, a rounded angle widely separated from the first but a 
connected therewith by a continuous valley and reaching nearly age 
from the median line as angle No.3; 3, 4 and 5, large equidisiam™ 
acute triangles of equal size, much larger and longer than opp 
outer triangles and separated therefrom by a zigzag median lin e u & 
amel forming the alternating bases of opposing series of triangles; = A 
the inner angle of posterior loop. Exteriorly the angles are form 
as follows: 1. a rounded corner at the outer base of anterior opi 
asmall angle abutting on the extended valley of auterior p T 
angle being anterior to plane of angle (No. 2) of the oppo E 
a rounded angle, widely separated from angle No. 2 of same a s 
to the extreme posterior deflection of the crescent-like B | 
w Vi Re: 
angle No. 3 terminates; this loop is connected by a narro 2 
the anterior loop and in like manner with its preceding angle on ; 
the same side and the two opposing angles, the five angles par d f 
nected representing the four normally present in the anterior imi | 
recent Arvicola, Evotomys, Synaptomys, Myodes and Cuniculus; °° 
