ORDER VIII. SCUTIBRANCHIATA.—ORDER IX. CYCLOBRANCHIATA. 235 
ORDER VIII. SCUTIBRANCHIATA. 
These Gasteropods are clothed with shells quite open, and the greater 
number are not in any degree spiral, and cover the animals in the manner 
of a shield. 
They are separated into two great genera: Haxroris and FissureLLA, 
the first of which is the most richly embellished of the class. 
ORDER IX. THE CYCLOBRANCHIATA. 
These animals have their branchiw in the form of little leaflets, or pyra- 
mids, attached in a circle, under the margins of the cloak. There are 
only two genera: PaTeiia, the Limpets, and Cuiron, the Chitons. 
The Limpets live on rocks or stones, to which they cling so fast by 
suction, that it requires the introduction of a knife between the shell and 
the stone to detach them. It has been calculated that the larger species 
are thus able to produce a resistance equivalent to a weight of one hundred 
and fifty pounds, which, considering the sharp angle of the shell, is more 
than sufficient to defy the strength of a man to raise them. They often 
congregate in large numbers in one place, and an old writer compares them 
to nail-heads stuck into the rock. They live upon the green sea-weed, that 
we find covering at ebb tide the stones with a thin emerald layer; and when 
these are submerged by the flood, they creep along on the bottom, slowly 
grazing on these marine pasture-grounds. 
The Gasteropods surpass all the Molluscous animals in the beauty of the 
form of the shells, and the splendor and delicacy of their colors. The 
Haliotides ave handsome mother-of-pearl shells, frequently used for the 
inlaying of boxes. If the spiral shells could be drawn out, they would 
all be found to consist of a tube gradually widening from the apex to the 
base. “ But,” says an enthusiastic conchologist, “ what an immense variety 
of forms and ornaments, what a prodigality of splendid tints, has not 
Nature spread over their countless species!) The same fundamental idea 
appears to us in a thousand different forms, one still more elegant, in com- 
parison, than the other. Thus the passion of the shell-collector is as con- 
ceivable as that of the lover of choice flowers; and when we hear that rich 
tulip amateurs have given thousands of dollars for a single bulb, we cannot 
be surprised that hundreds are paid for the Scalaria pretiosa, or the Cy- 
prea aurora, which the New Zealand chiefs used to wear about their 
