Geology and Natural History. 73 



II. A Lower Silurian (Ordovician) fauna came from Portezuelo 

 near Salta, in the province of the same name, and from Mudana 

 in the province of Jujuy. The first was in a firm yellow quartz 

 sandstone; and the second from a fine-grained, micaceous, some- 

 what slaty, yellowish grey sandstone. The fossils noted are 

 Megalaspis sp., Better ophon sp. and Didymograptus sp. 



III. Another Lower Silurian fauna was obtained from a lime- 

 stone in Cerro del Fuerte, east from Jachal in the province of 

 San Juan. This fauna contains the species Illaenus Argentinus 

 n. sp., Maclurea Avellanedce Kays., Leptmna serieea Sow., and 

 Orthis calligramma Dalm. ? 



IV. The Devonian fauna occurs at several horizons in a series 

 of rocks lying apparently comformably upon the Lower Silurian 

 limestones, in the neighborhood of Jachal. The chief locality is at 

 Cerro del Fuerte, east of the Jachal River. The rocks are de- 

 scribed by Bodenbender as about 400 meters thick. The lower 

 200 m. consists of barren clay slates. In the upper 200 m. of 

 slates and grauwacke there are three fossiliferous horizons. 

 The lower zone contains Leiorhynchus Bodenbenderi and Lepto- 

 coella acutiplicata \ the middle zone contains besides the same 

 Leptocoelia, also, Ghonetes fuertensis, Bhacops, Homalonotus, 

 Tentaculites, Better ophon, etc. ; the upper zone contains Spirifer 

 antarcticus (=chuquisaca) , Chonetes folklandica, Vitullna pus- 

 tidosa and several bivalves. 



The second locality is west of the Jachal River, at Cerro del 

 Aqua Negra and at Cerro Blanco. The formation here is 2000- 

 3000 m. thick, and is composed of grauwache, sandstones, quartz- 

 ites, slates and very subordinate beds of limestones. At the 

 Cerro del Aqua Negra locality only the first fauna appears with 

 Leior. Bodenbenderi, Leptoc. acutiplicata and Tropidoleptus 

 fascifer. At Cerro Blanco two higher faunas appear, the lower 

 marked by numerous remains of Lingula subalveata and Bhola- 

 della radiata, and the upper by numerous conularia, starfish, 

 crinoids, Spirophyton, etc. 



The list of species of the Devonian fauna is as fellows, viz : 

 Cryphceus sp., Bhacops cf. rana Green, Homalonotus sp., Ortho- 

 ceras sp., Naticopsisf sp., Bellerophon sp., Bellerophon aff. Mur- 

 chisoni d'Orb., Conularia Quichna A. Ulrich ?, Tentaculites sp., 

 Leptodomus sp., Bholadella radiata Hall., Allerisma ? sp., Tro- 

 pidoleptus fascifer n. sp., Liorhynchus Bodenbenderi n. sp., Lior- 

 hynchus f Brachebuschi n. sp., Meristella? sp., Beptocoelia acuti- 

 plicata Conr., Vitidina pustulosa Conr., Spirifer antarcticus 

 Morr. et Sharpe, Orthothetes sp., Orthothetes cf. arctostriatus Hall, 

 Chonetes folklandica Morr. et Sharpe?, Chonetes fuer ten sis n. sp., 

 Chonostrophia sp., Lingula (Dignomia) subalveata n. sp., Orbi- 

 culoidea cf. humilis Hall. 



V. A few fossils of Devonian age are described from Coloolo 

 and Chililaya, two points near the shores of the Titicaca sea. 

 The rock in the first case is a hard blackish slate, the second is a 

 yellowish, fine, sandy clay rock. The fossils reported are Horn a- 



