242 
Miscellaneous. 
that in the larva under consideration there is any act which alto- 
gether is comparable to what happens among the true ruminant 
quadrupeds. From their structure however, their physiological 
action and their development, these multiple stomachs of the gnat 
call to mind, but on a small scale, what is observed on the * rumen ’ 
and * reticulum ’ of the ruminants. In fact their inner membrane 
is finely alveolated like that of the paunch in these large animals, 
and the nutriment does not pass by these vesicles as if it were a 
simple canal, which is generally the case, but it is conveyed into 
them by a particular passage ; it sojourns there for a longer or 
shorter period, experiences a certain elaboration, and is then ex- 
pelled by the same passage and re-enters the intestinal tube. The 
nutriment does not return, it is true, to the mouth, but it undergoes a 
certain alteration in the stomachs, for the particles partially digested 
which are perceived in the intestine are considerably thinner than 
those in the gastric vesicles. In the first periods of life the rumi- 
nants feed solely upon milk, there is as yet no rumination in them, 
and the two first stomachs are then proportionately very small ; this 
is likewise the case in the very young larvae of the gnat, as they 
immediately after their issue from the egg absorb a very thin and 
almost entirely fluid nutriment ; these organs are at this period simply 
rudimentary and perfectly impermeable. The thorax itself which 
contains them is proportionately much smaller than in larvae of a 
greater age. 
Thus, if the comparison between the digestive function of the vesi- 
cular stomachs of the gnat and the physiological action of the two 
first digestive cavities of the ruminants is not perfect, however di- 
stant these animals are in the zoological scale, yet it cannot be denied 
that in a local physiological point of view there is rigorous analogy. 
It is moreover highly worthy of attention that these stomachs are 
absolutely analogous by their form, their position, and the manner 
in which they act, to the stomachs of the polygastric Infusoria de- 
scribed by Ehrenberg. This fact adds a fresh proof, although observed 
upon other animals, of the truth of the investigations of that scientific 
naturalist. — Comptes Rendus, Oct. 25, 1847. 
Description and Anatomy of a new and curious subgenus of Planaria. 
By Joseph Leidy, M.D. 
In October 1840, Prof. S. S. Haldeman published a description of 
an animal under the name of Planaria gracilis*. Upon examination 
I detected such a remarkable peculiarity in the digestive apparatus 
as led me to investigate its anatomy in detail, and to form for it a 
separate subgenus, characterized as follows : — 
Phagocata, oblonga, plano-convexa, nuda, contractilis, mucosa, an- 
tica auricularia. Aperturse duae, ventrales, ad os et generationem 
pertinentes. Proboscides multae. 
* Supplement to No. 1 of “ A Monograph of the Limniades, or Fresh- 
water Univalve Shells of North America, containing descriptions of appa- 
rently new animals in different classes,” &c. By S. S. Haldeman. Phila- 
delphia, 1840. 
