BOOK TWELFTH. 
CRUSTACEA. 
CLASSIFICATION. 
§ 262. 
In the Classification of the Crustacea, the remark of Erichson® should 
be adduced, that, with these animals, the external locomotive organs are not 
‘limited, as with the other Arthropoda, to the anterior part of the body, 
but may exist on all its segments, and often with a shape so changed, that 
they become foot-jaws, or anal-feet, or oars. If the Crustacea are ex- 
amined from this point of view, it will not appear surprising that the 
Myriapoda are classed among them; for they do not properly belong 
either to the Arachnoidae or to the Insecta. 
ORDER I. CIRRIPEDIA. 
Famity: Batanopga. 
Genera: Balanus, Chthamalus, Coronula, Tubicinella. 
Famity: Lepapga. 
Genera: Otion, Cineras, Lepas, Pollicipes. 
ORDER If. SIPHONOSTOMA. 
Famity: Penevira. 
Genera: Penella, Peniculus, Lernaeocera, Lernaea. 
Famity: Lernaropza. 
Genera: Achtheres, Tracheliastes, Brachiella, Lernaeopoda, Anchorella, 
Chondracanthus. 
Famity: Ereasrnria, 
Genera: Dichelestium, Lamproglena, Ergasilus, Nicothoé. 
1 Erichson, Entomographien, Hft. ¥. p. 12. 
