12 MIDLAND NATURALIST. 
by the oil globules abundantly found in the meshes of the proto- 
plasmic reticulum. 
As to the form of the animal it is more or less globose, and had 
it not been called Noctiluea—‘‘night light"—on account of its 
phosphorescence, one might, on account of its shape, have been 
tempted to name it “Sea-peach,” owing to its remarkable resem- 
blance to a peach, or apricot. Hertwig states that, in size, the 
animal may be one millimetre in diameter, but the largest that the 
author ever found, after examining thousands, was no greater than 
than 640 micra in diameter. 
The movement characteristic of the animals may be described 
as a rolling, swinging motion. They remain quite near to the 
surface of the sea, and in such numbers that they cover the upper 
Considering the fact that Noctiluca belongs to the unicellular 
animals, and that its structure is simple, it is still very striking. 
The animal is covered with a cuticle or cell-wall which we find to be 
about 1 to 2 u. in thickness. The author could make out no 
definite structure to this membrane, though from the observations 
of Cienkowski one would infer that Some structure exists. Cien- 
use his words, “eine viel jestere Consistenz als der Inhalt.” In fact, 
Butschli considers this cuticle identical with von Mohl’s “ primor- 
dial utricle,’ or with the "structured cell-wall” of Carnoy, in 
whether this holds good for the cuticle that covers the tentacle. 
appears in our illustration, this cuticle shows with marked 
distinctness around the tentacle, and we would be inclined to think 
that at least here the cuticle is chemically and physically different 
from that which covers the rest of the animal. 
A noticeable external structure of the animal is the groove 
which extends about one fourth around the periphery, and may 
be termed the peristome groove, and is continued by an elevation 
for some distance. (Fig. 2, H.) 
The tentacle alread y mentioned is the most noticeable external 
able comment as to its origin, though no one has, in our Opinion, 
given a satisfactory explanation as to its homology. In fig, 2, we 
notice the striated appearance of this organ, the striations being, 
A 
