REVIEWS. 1 9 



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 

 histoiy, 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 



