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PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



[Nov. 21, 



CARBONIFEROUS. 



From the small basin of these rocks at the Isthmus of Copacabana, 

 in the Lake of Titicaca, the following species were obtained : — 



Productus semireticulatus, Martin. (P. Inca, D'Orb.) PI. IV. fig. 1. 

 Longispina, Sow. (P. Capacii, D'Orb.) PI. IV. fig. 2. 



Spirifer Condor, D'Orb. {Sp. Jtriatus, Sow. ?) 



Boliviensis, D'Orb. 



Orihis resupinata, Sow. ? 



Andii, D'Orb. (from a Santa Cruz specimen). PI. IV. fig. 3. 



Aihyris subtilita, Hall. (Ter. Peruviana, D'Orb.) PI. IV. fig. 4. 



Bhynchonella (a species with three raised ribs, very like some va- 

 rieties of B. Pleurodon ; also from a good Santa Cruz specimen). 

 PI. IV. fig. 5. 



Euomphalus, with separated whorls (possibly a Phanerotinus). 

 BelleropJion, sp. ; a close ally of B. TJrii, Flem. PI. IV. fig. 6. 



Corals, also, and Crinoids, all imperfect. D'Orbigny describes a 

 Favosites and a Cup-coral, a Fenestella, &c. ; and Col. Lloyd's col- 

 lection from Arqne, as well as Mr. Cumming's from Santa Cruz, both 

 include such specimens. I see no essential difference between the 

 Productus semireticulatus, so common in Britain, and the so-called 

 P. Inca of D'Orbigny ; and I think it would puzzle any one to draw 

 a clear distinction between his P. Capacii and our own familiar 

 P. Longispina, found everywhere in the Carboniferous Limestone. 

 The Spirifer Condor has certainly rougher ribs than the ordinary 

 varieties of Spirifer striatus, and may be distinct. We figure (PI. IV. 

 fig. 3) one remarkable form, said to be from Santa Cruz, but, at all 

 events, from the Carboniferous Limestone of the Andes, of which less 

 perfect specimens occur in Mr. Forbes's collection. It is a beau- 

 tiful species of the Orthis resupinata group, and has received the 

 absurd name of 0. Andii from D'Orbigny. 



Our figure of the Bhynchonella (PI. IV. fig. 5) is also from this 

 collection, which was sent home by Col. Lloyd many years back. 



DEVONIAN*. 



Orthis, sp. PI. IV. fig. 7. 



Lnternal casts only. It belongs to the group of Orthis resupinata 

 and 0. Michelini, and thus may be either Carboniferous or Devonian. 



Locality. Oruro. Sent from thence by Col. Lloyd. (Mus. Prac- 

 tical Geology.) 



* Of the seven species considered Devonian by D'Orbigny, only' four appear 

 to be certainly supra-Silurian ; and these four may (from their type) be either 

 Devonian or Carboniferous. They are — Bhynchonella Peruviana, Spirifer Boli- 

 viensis, S. Quichua, and Orthis Inca. Spirifer Quichua is from Chuquisaca, the 

 other three from Cochabamba. 



The Orthis pectinata, on which D'Orbigny lays stress, seems to me to be very 

 unsatisfactory. It is only the cast of a single valve, without hinge or teeth, of a 

 shell destitute of any marked characteristics. I should not like to speculate as 

 to its age ; but M. D'Orbigny may have seen Devonian species like it. 



