REVIEWS. 
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belong to Cuvier’s second division of the animal kingdom—viz., the Mollusca 
-—and came under the denomination of multivalve shells; which term was 
applied by the great Swedish naturalist, not only to those animals which 
really belonged to the Testacese, but also to the Cirripedes, which have 
nothing whatever to do with shells, properly so called. It was not, how¬ 
ever, until Mr. V. Thompson’s splendid discovery of the larva in the last 
stage of development in the Balanus, that this sub-class received its proper 
place in the third division of Cuvier—namely, the Articulata—and in the 
class Crustacea. This error in classification is not surprising when we 
consider the fixed condition of their shell, and the degree of external resem¬ 
blance between, on the one hand, Lepas and Teredo, and, on the other 
hand, between Balanus and a Mollusc, compounded of a patella and chiton. 
It is remarkable that Cuvier, although aware of their internal structure, 
allowed the external false resemblance to the Mollusca to counterbalance 
the opinion which his knowledge might have arrived at. 
Straus, who was an eminent and philosophic writer, remarkable for his bold 
deductions and able generalizations, was supposed to have been the first 
who, in 1819, maintained that the Cirripedes were most nearly allied to 
the Crustacea; but this view was disregarded until Mr. Thompson’s dis¬ 
covery, just alluded to, about eleven years afterwards; since that time, with 
trifling exceptions, the Cirripedes have been almost universally admitted 
among the Crustacea. 
In the present able Monograph Mr. Darwin divides the Cirripedia into 
three orders—viz., the Thoracica, Abdominalia, and Apoda—between 
which the fundamental difference consists in the limbs or cirri being tho¬ 
racic in the first, abdominal in the second, and entirely absent in the third. 
The Cirripedes are commonly bisexual or hermaphrodite ; but in some 
genera the sexes are separate. The males in these genera are minute— 
often exceedingly minute—and, consequently, more than one is attached to 
a single female. In several species they are short-lived ; for they cannot 
feed, being destitute of a mouth or stomach. In those genera it is the 
females which retain the characters of the genus, family, and Order to which 
they belong—the males often departing widely from the normal type. 
Perhaps among all the wonders that we occasionally hear of in natural 
history, none are so strange or so startling as the description of the males 
of the Cirripedes. In some cases they are rudimentary to a degree, 
unequalled in the whole animal kingdom, so as to exhibit, in fact, nothing 
but mere bags of spermatozoa. For example, the male Alcippe has no 
mouth, no stomach, no thorax, no abdomen, and no appendages or limbs 
of any kind! After such a surprising amount of abortion, Mr. Darwin 
