1904-1905.] 331 



guesswork, and to decide upon their generic relationship with 

 any approach to certainty is also often very difficult. The 

 teeth vary so much in form and proportions in different parts 

 of the mouth, and some well-defined genera and species differ 

 so little from one another in their dentition, that a scientific 

 nomenclature is sometimes quite impossible. Such teeth form 

 part of the fauna of our Cretaceous rocks. The fish remains 

 recorded by Mr. R. Bell consist of teeth of the families 

 Lamnidce and Myliohatidw. The LamnidcB are represented in 

 our Ctetaceous formations by four genera: — 1st genus Scap- 

 anorhynchus — Scapanorhynchus rapliiodon, Inoceramus crispi- 

 hand, from Chloritic sands, Woodburn Glen; Scapanorhyn- 

 chus gigas, Rhynchonella rohusta-hand^ from Chloritic sand- 

 stone, Kilcoan. 2nd genus Oxyrhina — Oxyrhina angustidens, 

 Exogyra columha-band, from Chloritic Sands, Colin Glen. 3rd 

 genus — Lamna appendiculata, Rhynchonella robusta-hand, 

 from Chloritic sands, Waterloo, Lame. 4th genus Corax — 

 Corax falcatus, Inoceramus crispi-hand, from Chloritic sands, 

 Squire's Hill; Corax affinis, from Spongarian band, Chloritic 

 sands, Kilcoan. The family Myliohatidce — The following species 

 of the genus Ptychodus were recorded also by Mr. Bell: — 

 Ptychodus decurrens, Inoceramus crispi-hand, from Chloritic 

 sands, Hillsport ; Ptychodus mammillaris, from Nodular-band, 

 Chloritic chalk, Squire's Hill; Ptychodus latissimus, from 

 Spongarian band, Chloritic sandstones, Hillsport. Teeth 

 form most important guides to the naturalist in the classifi- 

 cation of animals, and their value is enhanced by the facility 

 with which, from their position, they can be examined in 

 living or recent animals; whilst the durability of their tissues 

 renders them not less available to the palaeontologist in the 

 determination of the natural affinities of extinct species, of 

 whose organisation they are often the sole remains discover- 

 able in the deposits of former periods of the earth's history. 

 Mr. Bell exhibited a number of exceedingly fine examples of 

 Cretaceous fossils which he had collected himself along our 

 local Antrim hills. The paper was listened to with great 

 interest and followed by a brisk discussion. 



