﻿RHYNCHONELLIDtE. 



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R. ulotrix is easily distinguishable from R. radialis by its fewer and larger ribs, as 

 well as by other peculiarities. 



In recapitulation it may be mentioned that the most active research has not enabled 

 me to recognise more than seven or eight species of Athyris, and two of Retzia, in the 

 British Carboniferous deposits. These may be arranged in the following order, and those 

 that are most closely related have been connected with a brace : 



Athtris. 



Retzia. 



' 1 . Athyris planosulcata, Phillips. 



2. — lamellosa, L'Eveille. 



.3. — expansa, Phillips. 



4. — Royssii, L'EveillS. 



5. — squamigera (!) Be Koninck. 

 "6. — ambigua, Sowerby. 



7 . — globularis, Phillips. 



.8. — subtilita, Hall. 



(\. Retzi 

 12. — 



1. Retzia radialis, Phillips. 



ulotrix, De Koninck. 



Family — RHYNCHONELLID^E. 



The only two genera belonging to this family that have been hitherto discovered in 

 British Carboniferous strata are Rhynchonella, Fischer (' Introduction,' p. 93), and Cama- 

 rophoria, King ('Introduction/ p. 96, and 'Permian Monograph,' p. 23). The genus 

 Pentamerus has been recorded by Professor M'Coy, but the species so referred to belongs 

 to Cyrtina, and not Pentamerus, as will be found explained at p. 66 of the present 

 Monograph. 



After a very lengthened and difficult study of the various species of Rhynchonella and 

 of Camarophoria stated to have been found in the Carboniferous rocks of Great Britain, 

 I have ventured to refer the whole to the following species : 



Rhynchonella. 



1. Rhynchonella reniformis, Sowerby. 



2. — cordiformis, Sowerby (still doubtful). 



3. — acuminata, Martin. 



4. — pugnus, Martin. 



5. — pleurodon, Phillips. 



6. — flexistria, Phillips. 



7. — angulata, Linnaeus. 



V 8. — trilatera, De Koninck. 



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