394 ARTHROPODA. 



are littoral in their habits, and have legs formed for walking. 

 Others are adapted for swimming, and the Land-crabs habit- 

 ually live inland. 



As before remarked, the Brachyurous Decapods are much 

 later in their appearance than the Macrura. With the ex- 

 ception the minute Hemitro- 

 chiscus paradoxus of the Per- 

 mian, and the still more ancient 

 BracJiypyge carbonis of the Car- 

 boniferous, the oldest known 

 Crab, at present, is the Palce- 

 inachus longipes, described by 

 Dr Henry Woodward from the 

 ForestMarble (Lower Oolites). 

 In the Cretaceous series Crabs 



^ tolerably abundant , 0116 



Cretaceous form belonging to 



the recent genus Cancer. In the Tertiary rocks, and espe- 

 cially in the London Clay (Eocene), remains of Crabs occur 

 in profusion. The chief Tertiary genera are Xantlwpsis, 

 Xantholites, Cancer (fig. 249), Grapsus, and Ebalia. 



LITERATURE. 



GENERAL. 



1. " Glieder-fiissler : Arthropod a/' in ' Bronn's Klassen und Ordnun- 



gen des Thier-Reichs.' Gerstaecker. (Not yet completed.) 



2. Article " Crustacea," in * Encyclopaedia Britannica/ 9th ed. vol. 



vi. Henry Woodward. 1877. 



3. Article " Crustacea." ' Todd's Encyclopaedia of Anatomy and 



Physiology. 3 Milne-Edwards. 1835. 



4. " Histoire Naturelle des Crustaces." Milne-Edwards. 1834-1840. 



5. " Histoire Naturelle des Crustaces fossiles." Brongniart and Des- 



marest. 1822. 



6. " Catalogue of the British Fossil Crustacea." Henry Woodward. 



1877. 



ClBRIPEDIA. 



7. " Monograph of the Cirripedia." Darwin. ' Ray Society.' " Lepa- 



didse," 1851. " Balanidaa," 1854. 



8. "Fossil Lepadidee of Britain." Darwin. ' Palseontographical 



Society.' 1851. 



