Ch. XIY.] 



FOSSILS OF THE SUFFOLK CEAG. 



in 



and of whicli a fragment (the Hempstead beds of Forbes) escaped denu- 

 dation in England. 



The distinctness of the fossils of the Coralline from those of the Red 

 Grag, arises in part from their higher antiquity, and, in some degree, from 

 a difference in the geographical conditions of the submarine bottom. The 

 prolific growth of corals, echini, and a prodigious variety of testacea and 

 bryozoa, implies a region of deeper and more tranquil water ; whereas, 

 the Red Crag may have been formed afterwards on the same spot, when 

 the w^ater was shallower. In the mean time the climate may have become 

 somewhat cooler, and some of the zoophytes which flourished in the first 

 period may have disappeared, so that the fauna of the Red Crag acquired 

 a character somewhat more nearly resembling that of our northern seas, 

 as is implied by the large development of certain sections of the genera 

 Fusus, Buccinum^ Purpura^ and Trochus^ proper to higher latitudes, and 

 which are wanting or feebly represented in the inferior crag. 



Some of the corals and bryozoa of the lower Crag of Suffolk belong to 

 genera unknown in the living creation, and of a very peculiar structure ; 

 as, for example, that represented in the annexed fig. (154), which is one 



Fig. 154 



Fascicularia atirantmm,, Milne Edwards. Family, Tudidiporidm, of same author. 



Bryozoan of extinct genus, from the inferior or Coralline Crag, Suffolk. 



a. Exterior. b. Vertical section of interior. c. Portion of exterior magnified. 



d. Portion of interior magnified, showing that it is made up of long, thin, straight tubes, 

 united in conical bundles. 



of several species having a globular form. The great number and variety 

 of these zoophytes probably indicate an equable chmate, free from intense 

 cold in winter. On the other hand, that the heat was never excessive is 

 confirmed by the prevalence of northern forms among the testacea, such 

 as the Glycimeris, Ci/prina, and Astarte. Of the genus last mentioned 

 (see fig. 155) there are about fom'teen species, many of them being rich 

 in individuals ; and there is an absence of genera peculiar to hot climates, 

 such as Conus, Ollva, Mitra, Fasciolaria, Crassatella, and others. The 

 cowries [Cyprma^ fig. 153), also, are small, and belong to a section (Trivia) 

 now inhabiting the colder regions. A large volute, called Vohita Lam- 

 herti (fig. 156), may seem an exception; but it differs in form from the 



