ANNIVERSARY ADDRESS OF THE PRESIDENT. 



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history. Probably the Upper Llandovery rocks of Ireland yield 6 

 or 8 species, the Girvan beds about 30, the Gala group the same, the 

 Mulloch beds 25 species, and the Conistonbeds 25 species ; but many 

 also belong to the Lower Llandovery below and elsewhere. The species 

 in two of the genera above named, Monograptus and Cyrtograptus, 

 increase in the Wenlock ; in which, if we include the species which 

 occur in the Tarannon Shales lying at the base of the Upper Silurian 

 (Lower Wenlock group), some 9 genera and 20 species may occur. 

 As in the Caradoc, it is extremely difficult to arrive at the number 

 of true species that range through the areas, owing to not having 

 correct knowledge of the species. 



Actinozoa. — This is, zoologically, an important group in the Upper 

 Llandovery, from the number of genera occurring and the numeri- 

 cally few species, 11 of the 16 genera being represented only by 



1 species each. These are Alveolites, Coenites (probably one genus), 

 Holy sites. Labechia, Ompliyma, Plasmopora, Ptyehophyllum, Lincl- 

 strbmia, Propora, Pinnaeopora, and Streptelasma. Thus only 5 

 genera constitute a specific fauna, viz. Favosites 4 species, Heliolites 5, 

 Palceocyclus 2, Petraia 7, and Syringopora 3. Their dispersion or 

 distribution is equally significant, showing that the two chief com- 

 pound genera, Favosites and Heliolites, are, with one exception 

 {Petraia), the most widely distributed geographically. Petraia 

 occurs in all the 14 localities * ; and perhaps no single genus has so 

 wide a range or such persistent representative forms, commencing 

 in the Caradoc with 6 species, having the same number in the 

 Lower Llandovery, and 7 species in the Upper Llandovery. It is 

 reduced to 3 in the Wenlock, and 1 (P. bina) in the Lower Ludlow. 

 "We know also of 3, if not 4, Petraia in Lower, Middle, and Upper 

 Devonian ; they are, however, distinct species, being P. celtica, 

 Lonsd., P. gigas, M'Coy, and P. pleuiradialis, Phil. As regards the 

 number of genera and species numerically of value, or important 

 in certain areas, we find that in Pembrokeshire and Cardiganshire 

 these are but feebly represented. The former county, at Marloes 

 Bay, has given us 3 genera and 4 species, viz. Favosites asper, 

 Ompliyma iu.rbinata, Petraia bina, and Petraia subduplicata; and 

 Cardiganshire only 1, Petraia elongata. Radnorshire has yielded 



2 genera and 3 species, Heliolites inter stinctus, Petraia elongata, 

 and P. subduplicata. These few and local species are significant 

 and suggestive as to the cause of their restricted numbers. 

 Worcestershire, through the Malvern area, is richest in species, its 

 7 genera and 18 species being the highest known in the nine areas — 

 Caermarthenshire and Caernarvonshire having 12, Gloucestershire, 

 Scotland, and Ireland each 10 species, and South Wales generally 14. 

 Of the 16 genera and 32 species that range through the Upper Llan- 

 dovery beds, 14 genera and 22 species pass up into the Wenlock. The 



3 genera peculiar to this horizon are Propora (P. Edwardsii), Pina- 

 copora (P. Andersoni), and Lindstrdmia (L. lazvis). The remaining 

 genera and species all pass to the Wenlock series, the Coelenterate 

 fauna of which numbers 76 species. 



* P. subduplicata has recently been discovered in Scotland. 



