94 GUIDE TO THE FOSSIL INVERTEBRATE ANIMALS. 



Gallery cods are too small for satisfactory exhibition, so that only 

 a small selected series is shown. 

 Table-case The ClRRIPEDIA, or barnacles and their allies, long the 

 Wall^case ^®^^o^^ folk-lorists, are of special interest to British 

 13b, c. naturalists as having formed the subject of two monographs, 

 on the recent and fossil forms respectively, by Charles 

 Darwin. They have also a peculiar interest as representa- 

 tives of a free and actively moving group of animals that, so 

 soon as their early wandering days are over, settle down to a 

 fixed existence, becoming permanently attached by the fore- 



FiG. 46. — Fossil Crustacea, 1, a Brachyuran Decapod of the tribe Dro- 

 miacea, Dromilites Lamarcki, London Clay. 2, a Brachyuran Decapod 

 of the tribe Oxystomata, Palmocorystes Stokesi, Gault and Upper 

 Greensand. 3, a Macruran Decapod of the tribe Eryonidea, Eryon 

 arctiformis, Solenhofen Stone. 4, a Macruran Decapod of the tribe 

 Loricata, Mecochirus longimanus, Solenhofen Stone. 5, an Ostracod, 

 Cypridea tuherculata, Wealden. 6, a Cirripede, Loricula pulchella, 

 Turonian Chalk ; the specimen was figured by C. Darwin. AH figures 

 except 5 and 6 are considerably less than natural size. 



part of the head to rocks, shells, drift-wood, ships, and the 

 like. Some, as the common Balani or acorn-shells of our 

 coasts, are closely and immediately attached to the rock or 

 wood ; others, as the barnacles, hang from a long stalk. In 

 either case they develop a calcified shell composed of a 

 number of definite pieces. Six pairs of feathery cirrus-like 

 limbs, to which the Sub-Class owes its name, stretch out 

 from the shell, and continuously sweep food-particles to the 

 mouth within the shell. This return to a mode of feeding 

 characteristic of creatures fixed to one spot is accompanied, 

 as in all such creatures, by a tendency towards radiate 

 symmetry. In spite of this remarkable modification, Cirri- 



