ANNIVERSARY ADDRESS OP THE PRESIDENT. 



209 



through the Pentremitidae, 1 6 species, and Pentaphyllum 1 species, 

 are all confined to the Carboniferous Limestone proper. The sin- 

 gular group of the Perischoechinoidea, with Palcechinus 7 species, 

 Perischodomus and Melonites 1 each, also essentially characterize the 

 Carboniferous Limestone proper. 



Annelida. — 34 species of this class, belonging to 13 genera, wander 

 through the 8 divisions. Spirorbis numbers 14 species and Serpida 6 ; 

 the remaining 11 genera have only 1 or 2 species each. Serpulites 

 carbonarius, Spirorbis pusillus, S. caperatus, and S. lielicteres are the 

 only 4 species that range above the Carboniferous Limestone and into 

 the Coal-measures where the argillaceous shales and clays are of 

 marine or estuarine origin. The Calciferous Sandstones of Scot- 

 land, through the researches of Bennie, have yielded Serpidites 

 carbonarius, Spirorbis Eichwaldi,S. globosus, S. lielicteres, S. pusillus, 

 and 2 varieties. 16 species occur in the Lower Limestone Shale ; 

 10 genera and 24 species in the Carboniferous Limestone. Serpulites 

 membranaceus is the only Yoredale form ; and 4 species, Crossopoclia 

 Embletonios, C. media, Serpulites carbonarius, and Spirorbis pusillus, 

 occur in the Millstone Grit ; and Serpulites carbonarius is the only 

 Lower Coal-measure form, also associated with Arenicola carbonaria. 

 The same 2 species are Middle and Upper Coal-measures, which 

 exhausts the Annelidan fauna. 



Crustacea. — The remarkable Crustacean fauna that occurs in the 

 Silurian rocks numbers about 320 species, chiefly Trilobites, all of 

 which, with the exception of 5 or 6 genera, died out entirely at the 

 close of the Silurian period. The Crustacea of the Old Red Sandstone 

 belong chiefly to the order Merostomata — Eurypterus, Pterygotus, and 

 Stylonurus being the characteristic genera. The Trilobita, comprising 

 only 6 genera (Bronteus, Cheirurus, Harpes, Homalonotus, Phacops, 

 and Phillipsia), with 11 species, are Devonian, no Trilobite occurring 

 in the Old Red proper. The Carboniferous system in Britain yields 

 33 genera and 225 species, 130 of which are Ostracoda, 59 Phyllopoda, 

 2 Merostomata, 6 Poecilopoda, 2 Stomapoda, 5 Macrura, and 13 Tri- 

 lobita, illustrating the 3 genera, B^achymetopus (2), Grijjithides (5), 

 and Phillipsia ( 6), which group entirely disappears with the close 

 of the Carboniferous Limestone. Nowhere in Europe or America 

 have we evidence of the continuity of this group above the rocks 

 named. Beyond the Ostracoda and Phyllopoda, which constitute 

 the 2 important orders in the Carboniferous rocks (together num- 

 bering 189 species out of the 225 known), there is little to discuss. 

 The genera of Ostracoda number 85, the Phyllopoda 8, the Trilobita 

 only 3. 



The Calciferous Sandstone (Tuedian) has yielded 9 genera and 

 20 species, mostly Ostracoda, and 2 species of Anthrapalcemon, the 

 first known appearance of the group or tribe Macrura. (3 other 

 species of the same genus occur in the Coal-measures.) 



Lower Limestone Shales. — 1 7 genera and 48 species, also chiefly 

 Ostracoda and Phyllopoda, are individually abundant in the Lower 

 Carboniferous beds (below the Carboniferous Limestone). 



Carboniferous Limestone. — 159 species are recognized and de- 



