PALAEONTOLOGY 



groenlandica, Natica catena, N. clausa, and Paludina media. A lamp- 

 shell, Rhynchonella psittacea, is of occasional occurrence. 



Passing from the Tertiary to the Secondary deposits, the most 

 interesting vertebrate remains from the Norfolk Chalk are teeth of 

 Liodon anceps, a large marine lizard-like reptile allied to the well-known 

 Mosasaurus of the Upper Cretaceous beds of Belgium. Certain other 

 teeth of the same general type, as well perhaps as vertebra, may indicate 

 a species of the last-named genus in the Chalk of the county. Vertebras 

 from the White Chalk have been referred to Ichthyosaurus campylodon, and a 

 single tooth of the same genus from the Red Chalk of Hunstanton, 

 preserved in the Woodwardian Museum, Cambridge, has been made the 

 type of an undescribed species, under the name of /. angustideus . 



Of the cretaceous fishes found in the county, the following are the 

 more important. Firstly, we have a species described as Ccelorhynchus 

 cretaceus, the exact affinity of which is still uncertain. Teeth of the 

 chimasroid Edaphodon sedgwicki occur both in the Upper Chalk of 

 Norwich and in the Red Chalk of Hunstanton. A tooth in the British 

 Museum from the Upper Chalk of Norwich indicates a ray of the genus 

 Squatina ; and other teeth from the Whittington Chalk in the same 

 collection are referable to the pavement-toothed ray known as Ptychodus 

 decurrens. From the Chalk of Swaffham and Norwich have been 

 obtained teeth of a comb-toothed shark, Notidanus microdon ; and a species 

 of pavement-toothed shark, referable to the existing Australian genus 

 Cestracion, also occurs in the Norwich Chalk, as well as one pertaining to 

 the extinct genus Synechodus. Of sharks with a more normal type of 

 dentition, the following are represented in the Chalk of the county, viz. : 

 Scapanorhynchus rhaphiodon, S. subulatus, Lamna appendiculata, L. crassa, 

 Corax affinis, and C pristodontus. 



From the narrow strip of Kimeridge Clay near Downham Market 

 have been obtained the jaws of a peculiar species of ganoid fish which 

 has been named Caturus suchoides, this unique specimen being in the 

 British Museum. 



The invertebrate remains from the cretaceous rocks of the county 

 call, as a rule, for no special notice, since they are for the most part 

 identical with those from other districts. An exception must, however, 

 be made in favour of the vertical columns of enormous vase-shaped flints 

 met with at Horstead and certain other quarries in the county, for which 

 the Irish vernacular name paramoudra has been adopted. These flints, 

 which vary from two to five feet in height, have been formed by the 

 deposition of siliceous matter on large sponges somewhat resembling 

 the modern Neptune's-cup sponge {Poterium patera), as they gradually 

 became buried in the chalk ooze. As one individual became buried, 

 another grew in its place on the ocean floor, thus giving rise to the 

 vertical columns in which the paramoudras occur. Some of these flints 

 are pear-shaped rather than vase-shaped, and are hollow only in the 

 centre. Of molluscs, the commonest in the Chalk at Norwich are two 

 lamp-shells, Terebratula carnea and Rhynchonella plicatilis. 



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