828 Marvels of the Universe 
the form of a typical jelly-fish, and, like a jelly-fish, it progresses through the water by the 
alternate contraction and expansion of its cup-like body. 
Two other species 
again natives of tropical or sub-tropical seas and closely similar in form— 
do not swim, but creep, travelling, as a rule, slug-like over rocks and stones or over the mud of the 
sea-bottom, but often quitting the shore, they creep, back downwards, on the under-side of what is 
known as the “ tension-film”’ that forms all water surface. The one shown on this page is not 
floating, but thus “ creeping” ; and if it were to let go it would sink. They are about an inch in 
diameter and are brilliantly pigmented with scarlet, 
crimson, or yellow, and their long, retractile, feathery 
tentacles are snowy-white. 
In reproduction the Comb-bearers are peculiar. Eggs 
are set free in due season, and develop in the open sea, 
the young being very like the parent; but the first 
batches of eggs in the season are from undeveloped and 
otherwise immature individuals. Then there is a cessation 
of reproduction ; after this first effort at plenishing the 
earth—or rather the sea—they sink to the bottom and 
assume the fully adult form; then rising to the surface 
once more, they repeat the process. 
These little Comb-bearers are indeed worth the trouble 
of study. They are not the least of the Marvels of the 
Universe. 
THE STRUCTURD ANDI ORINAW ED NERO 
SisVEILILS 
BY BERNARD C. WHITE. 
INFINITE variety is the first impression received in the 
study of shells. This variety falls into the three groups 
of structure, ornament and colour. 
Definite causes would most certainly produce these 
results ; but while the variation from the original type 
can easily be detected, it is seldom possible to point out 
the causes, so varied and so subtle are their influences 
[Bu Theo. Carreras. 
BEROE. and so indefinite the period over which these influences 
One of the Sea-Gooseberries, though its share have extended. Let us investigate these structural 
is rather that of a Phrygian cap. It will attain 
some five or six inches in length, andiin eolourie changes a little; Probably the most primitives form ot 
Ro pies cans yaGn cure! Gln OF bits ox inell was Smyscl Wke a tent, altior tho shyle of a 
buff, overspread with a delicate tracery. i i i i 
limpet. Such a covering made for security, and all would 
go well until the creature within the shell desired to supplement its primitive organization. More 
room would then be wanted, and another story would be added, so that the tent-shape would become 
an elongated cone. Then the pinnacle, filled with the creature’s body, would possibly become too 
heavy to support its own weight, and would develop into a coil. In process of time this coil would 
be repeated as characteristic of the family, and the spiral shell would be evolved. 
At the top of page 831 are shown varieties of the tent-like construction. First is the Tooth Shell, 
which, however, must not be taken for anything allied to a limpet, for it is of an entirely different 
class. The snail has taken on entirely different habits, is a sand burrower, and has a different 
internal organization ; but it is quite possibly a development of a primitive form of tent-shell, 
narrow, elongated, as the homes of all the burrowers are, and inclining to a curve. Next is the 
