ANNIVERSARY ADDRESS OF THE PRESIDENT. 



157 



Euomphalus alatus, E. frenatus, E. sculptus, Holopella obsoleta, 

 Loceonema sinuosum, Murcliisonia articulate^ and Turbo tritorquatus. 

 jSTo form occurs in the Upper Llandovery of Cardiganshire. 



Pteropoda. — Only 1 species is known in the Upper Llandovery. 

 Conularia cancellated Sandb., occurs in Gloucestershire and Shrop- 

 shire, and is known in no other formations or localities in Britain. 

 The more abundant C. Sowerbyi is Lower Llandovery, Wenlock, 

 and Ludlow. It is questionable if 0. cancellata is really a British 

 species or only a variety of O. JSowerbyi. 7 of the 10 areas have 

 no represesentative of this group. 



Heteropoda. — Eccidiomplicdus (Cyrtolites) and Belleroplion, the 

 former having 2 species (E. Icevis, Sby., and E. scoticus), the latter 

 9, range pretty equally through the Upper Llandovery rocks, 

 B. dilatatus, B. trilobatus, and B. carinatus having the widest or 

 most extended geographical distribution. The rarer forms, Ecculi- 

 onvplialus scoticus, M'Coy, Belleroplion suhdecussatus, M'Coy, B. wen- 

 locfcensis and B. obtectus, PhilL, have as yet only occurred each in 

 one locality ; 5 of the 11 have appeared before in the Car ado c ; but 

 only one species, B. carinatus, seems to have been Lower Llandovery. 

 These Pelagic Mollusca, especially the family Afclantidse, have no fixed 

 habitat, their distribution being quite independent of the nature of 

 the sea-bottom, so that the Bellerophons of the Silurian. Devonian, 

 and Carboniferous periods occur indifferently in mechanical deposits 

 of the most varied petrological or lithological characters. The great 

 Porcellia (P. Woodivardii, Sby.) of the Middle Devonian, or the two 

 species P. striata and P. Symondsii of Phillips, occur in all sorts of 

 deposits all through the history of the genus, of which 12 or 14 

 species range from the Devonian to the Trias, Belgium having 

 afforded many forms. Conrad's genus Cyrtolites, probably the 

 Ecculiomplialus of Buckland, is represented in Britain by 3 species 

 — E. Bucklandi, Caradoc only; E. Icevis, Upper Llandovery, "Wen- 

 lock, and Ludlow ; and E. scoticus, Llandeilo, Caradoc, and Upper 

 Llandovery. Of the 11 Upper Llandovery species 6 pass to the Wen- 

 lock, 5 being species of Bellerophon, and 1 Ecculiomplialus {E. Icevis). 



Cephalopoda. — Of the 6 genera occurring in the Upper Llan- 

 dovery, viz. Actinoceras, Cyrtoceras, Lituites, Phragmoceras, Treto- 

 ceras, and Orthoceras, one (Actinoceras nummidarium) appears for 

 the first time, and the rare forms Phragmoceras compression and 

 Cyrtoceras approximatum have but local geographical distribution. 

 The last named is from the Upper Llandovery of Malvern only; 

 P. compressum the same, being of doubtful occurrence in the Ludlow 

 rocks. "We have seen that the Caradoc rocks of Shropshire have not 

 yielded a single species of Cephalopod ; but here, in the Upper Llan- 

 dovery of the same county, we have 3 genera and 9 species ; yet 8 

 genera and 47 species occur in the Caradoc rocks. This fact, coupled 

 with others to be arrived at through the tables of distribution, 

 tends to show the shallowing of the Caradoc sea and slow elevation 

 of the land through the latter part of the Caradoc period, and the 

 time represented by the deposition of both the Lower and Upper 



