THE CEPHALOUS MOLLUSKS. 237 
these mollusks exhibit to each other. They have carefully 
watched their communication among themselves, to discover if 
it were possible that the flame of love could exist in creatures 
so cold and slothful. The imagination has generally supplied to 
these observers that which they were earnestly wishing to see. 
We know nothing of their feelings, but in this we may rest 
assured, that the Creator has bestowed on every creature those 
capabilities of joy or sorrow which are exactly fitted to its organi- 
sation and the position it occupies in life. 
Allied to the cephala is a small tribe of mollusks which 
swim on the open seas by the aid of two wings, or membranous 
fins, which are situated on each side of the head. These expan- 
sions serve the double purpose of organs of respiration and also 
CLIO BOREALIS. 
of motion. The creatures, on account of these characteristic 
members, are termed Pveropoda (wing-footed). They have been 
compared to butterflies with expanded wings, but the comparison 
is not at all exact. One of the best-known pteropods is the 
Clio borealis, a pretty little creature with which the North Seas 
sometimes are perfectly swarming. The whales consume them 
in prodigious quantities; indeed, the sailors call them “ whales’ 
Sood.” 
Explorers of the Arctic Seas tell us, that often the desolate 
wastes of the northern waters are enlivened by the shoals and the 
movements of the clios; they dance and gambol on the surface 
of the calm seas, jumping out of the water like shrimps. These 
lively little Arctic people are beautifully tinted with blue, shading 
off to purple. Their head is a monument to the wisdom of the 
Great Creator. Six tentacles take their rise from the circum- 
ference of the mouth, upon each of which may be counted 3,000 
rough spots, under the microscope; these are found to be trans- 
