84 



Guide to the Invertehrata, 



CrAbs. Many crabs are met with in the Cretaceous formation, repre- 



6ALLEBT sented by PalcBOCorystes, Pliolophus, Eanina, Cyphoyiotus, Biaulax, 



East Side. D'^'omiopsis, Necrocarcinus, Orithopsis, and many other genera. 



Wall-«ase8 



12-14, 



Table- 



80-bd. 



Fig. 145. — Ehacliiosoma bispinosa, 11. Woodyr. Lower Eocene: Portsmouth. 



In the Tertiary strata crabs are exceedingly abundant, being 

 represented in the London Clay by the genera JRhackiosoma, 

 Plagiolophus, Litoricola, Necrozius, Xanthopsift^ Xanthilites, Loho- 

 carcinns, and many more. (See Table-case 84 and Wall-case 12.) 



Vermes — 

 ■Worms. 



GALLERY 

 VIII. 



Table- 

 case 79, 

 Wall-case 

 15a. 



Wall-case 

 16a. 



(Division B.— AT^ARTHEOPODA.) 



Y.—YEEMES— WORMS. 



As the worms are all soft-bodied animals, they are comparatively 

 seldom found in a fossil state. Their former existence is shown 

 by the tracks, burrows, and castings which they have left in the 

 wet mud and upon the ripple-marked sands of old seashores, 

 before these had become hardened into shales and sandstones. 

 More definite evidence is afforded by the small teeth which are 

 present in some forms, and by the tubes in which some of them 

 live. Such proofs of the former existence of worms are fairly 

 abundant, but their identification is very difiicult. The classifi- 

 cation of existing worms is based entirely on the structure of the 

 soft parts of the bodies ; it is only very rarely that any trace of 

 these is preserved in the fossils. The Eunice from the Pleistocene 

 deposits of Greenland and the specimens of Eunicites from the 

 Lithographic Stone of Solenhofen (in Wall-case 15a), are in as 

 perfect a condition of preservation as soft-bodied worms can be 

 expected to occur. jN"evertheles8, even in these cases, the genera 

 cannot be determined with certainty. 



