94 



PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



Heteropoda. — Belleroplwn ramseyensis, Hicks, B. solvensis, Hicks, 

 and B. shinetonensis, Call. ; the former both Menapian forms, cha- 

 racterizing the Tremanhire or Solva and Ramsey-Island beds, St. 

 David's. 



Cephalopoda. — None below the Upper Tremadoc. 



The analytical Table No. Y. shows that 28 genera and 58 species 

 occur in the Lower Tremadoc beds of North and South "Wales. Three 

 classes only are of numerical importance : — the Crustacea with 13 

 genera and 24 species ; the Brachiopoda, with 5 genera and 11 

 species ; the Lamellibranchiata, 5 genera and 12 species. These 

 3 groups constitute the mass of the known genera and species, or 

 23 out of 29 genera and 47 out of 59 species. 



Table V. — Lower Tremadoc. 



From 

 Upper 

 Lingula- 

 flags. 



Classes. 



Genera. 



Species. 



Pass to 

 Upper 

 Tremadoc. 





Plantas. 











Protozoa. 











Hydrozoa. 











Actinozoa. 













2 



2 







Annelida., 









4 

 4 





13 



24 



4 



4 



1 

 1 



Bryozoa. 



1 



1 









5 



11 



6 





Lamellibranchiata. . . 



5 



12 







Gasteropoda. 



1 











5 



1 

 3 







1 



3 







Cephalopoda. 









S 

 9 





28 



58 



9 



1 3 



Upper Tremadoc. 



Plants.— None. 

 Protozoa. — None. 

 Hydrozoa. — None. 



ECHINODERMATA. None. 



Annelida. — Tracks only. 



Crustacea. — 11 genera and 15 species constitute the Crusta- 

 cean fauna of the Upper Tremadoc ; 12 of the 15 species are Tri- 

 lobita ; the remaining 3, Ceratiocaris (2 species) and Lingulocaris, 

 are Phyllopoda, and the first of this order known in the British rocks. 

 Asaphus affinis, M'Coy, A. Homfrayi, Salt., Gheirurus Frederick Salt., 

 Bionide atra, Salt., Ogygia scutatrix, Salt., and 0. Selwynii, Salt., 

 pass to the Arenig, and, with 6 Brachiopoda and 3 Pteropoda, 

 constitute the 13 uniting forms out of a total of 182 species in the 

 Lower Cambrian rocks and 150 in the Arenig. 



The following 5 Crustacea only are confined to the Upper Tremadoe 

 — Angelina SedgwicJcii, Gonocoryphe olenoides, Olenus impar, Geratio- 



ris latus, and Lingulocaris lingulocomes. I am careful to name these 



