2 Transactions of the South African Philosophical Society. 
The most comprehensive work on the Cirripedia is from Charles 
Darwin,* who published a monograph of the class in 1854. From 
his book most of the following details are taken. Many members 
of the order are common on the rocks of the coast, on floating 
timber and ships’ bottoms, being known under various names, accord- 
ing to their shape and colour. Owing to the fixed condition of 
their shells and their external resemblance these animals were 
believed to be molluses until 1850 Vaughan Thompson recognised 
their crustacean nature by discovering their metamorphosis. 
The young larve when leaving the egg exhibit their true relation- 
ship very well. They move about freely until they find a suitable 
resting-place, where they attach themselves by means of their 
TUBICINELLA TRACHEALIS IN A PIECE OF WHALE SKIN, THE FRONT 
PORTION OF THE PIECE FOLDED BACK (natural size). 
1. Sheath of hardened epidermis, projecting beyond the surface. 2. Outer surface. 
3. Vertical section through epidermis. 4. Corium. 
antenne, or rather organs corresponding to the antenne of the 
crawfish, but assuming quite a different function. The larva 
changes at first into a kind of pupa, and finally into the complete 
cirripede. When this takes place they are still very small, only 
gradually reaching their final size. In order to attach themselves 
to suitable objects the cirripedes possess a so-called cementing 
apparatus. By means of a certain secretion they fix themselves on 
their. support. 
* “Charles Darwin.’ A monograph on theisub-class Cirripedia, with figures of 
all the species, the Balanide. London, 1854. ; 
