﻿I860.] 



SALTER — BOLIVIAN FOSSILS. 



09 



[The Aymara Indians are supposed to have been the original 

 inhabitants of these mountains. They still linger there, having 

 never been completely conquered, and never having amalgamated 

 with the Quichua or Inca race. — P. P.] 



Orthis, sp. PI. IV. figs. 15 & 16. 



A small Orthis, which may be equally compared with varieties 

 of the 0. elegavtula, Palm., or with the Pevonian forms, 0. opercu- 

 laris, &c, from the Pifel. The striae seem to be pretty regularly 

 interlined with smaller ones. In the absence of more perfect spe- 

 cimens, I do not give it a name. It is certainly not a young spe- 

 cimen of the 0. Humboldtii of P'Orbigny. 



Locality. Valley of Millepaya, and further south on the western 

 slope of Illampu. 



Strophomejta, sp. 



A mere fragment or two of a small thin-shelled species, with fine 

 radiating striae. 



Locality. Cotana, about five miles south of the town of Sorata. 



Ctjctjllella, sp. PI. IV. fig. 17. 



The transverse, oval and convex form of this shell reminds us of 

 0. ovata, Sow., rather than C. antiqua of the same author. Both 

 are Ludlow Eock species : but there are Lower Pevonian forms very 

 like them both in Britain and South Africa. The muscular plate ex- 

 tends, vertically, two-thirds across the shell. 



Locality. West face of Illampu. 



Cte^odonta (JSTucttla), sp. PI. IV. fig. 18. 



This is figured, because it is rather common. Such transverse 

 forms, concentrically striate, and a little antiquated in the lines of 

 growth, are known in all Palseozoic formations. 



Locality. Valley of Millepaya ; also further south, on the western 

 slope of Illampu. 



Arca ? Brownii, sp. PI. IV. figs. 19 & 20. 



Broad-oval, more than 2| inches wide, and 1-| deep ; the beak 

 at the anterior fourth not very prominent, the hinge -line tolerably 

 straight, not curved down. The posterior side is nearly as broad as 

 the depth of the shell beneath the beak, slightly angulated along 

 the posterior slope, and rounded at the posterior angle. The an- 

 terior side is somewhat produced, and straight along its hinge- 

 margin. Surface marked by rather distant lines of growth, and 

 covered all over the central parts of the disk by fine radiating stria?, 

 sharply impressed, very unequal in size and depth, wavy in their 

 course to the margin, and interlined by lesser ones. They are 

 altogether absent on the anterior and posterior fourth. On our 

 large specimen this effacement of the striae is gradual ; but in some 

 others it is sudden, and the central striated area in these specimens 

 is sunk below the general surface. These may be of a distinct species. 



