302 DESCRIPTION OF A COLLECTION OF FOSSILS, 



PART III. CARBONIFEROUS FOSSILS. 



The following little lot is, with the exception of a single species, from the 

 " Island of Titicaca in the lake of the same name, at an altitude of 4000 metres." 

 The geological age is fixed at once by the presence of the universally distributed 

 Fusulina cylindrica. The deposit consists of a reddish-brown and gray limestone, 

 and the genus Productus is well represented both in number of species and speci- 

 mens. 



TEREBRATULA, Briig. 

 T. TiTiCACENSis, n. s., PI. 42, fig. 11, 11a. 



Shell small, convex, subpentagonal ; beaks high, sides concavely sloping ; area 

 small ; surface covered only with fine lines of growth. Adult shell, large valve 

 with a deep median sinus, ending in a long, tongue-like projection of the base, 

 and bounded by two large rounded ridges; corresponding with this sinus, there is 

 one equally large ridge in the small valve. The presence of this sinus and ridge 

 cause the lateral margins of the valves to be strongly sinuous. In the young shell 

 the margins are straight and the sinus is wanting. 



Figures. Natural size. 



RemarJcs. Allied to T. Peruvianus, d'Orb., but larger and more regularly slen- 

 der. That species is referred by the author to the Devonian. 



RHYNCHONELLA, Fisch. 



R. Andit, d'Orb. (sp.). 



Terebratula, id., d'Orb., Amer. Merid. 45, PL 3, f. 14-15. 



Atrypa, id., d'Orb., Prod. Pal. Strat., v. 1, f. 14'7. 



PRODUCTUS, Sby. 



P. Cancrini, Terneuil, Geol. Russ., p. 273,, PI. 16, f. 8; PI. 18, f. Y. 



P. spinosus, Kutorga, Yert. der Min. Ges. St. Pet., 1842, p. 18, PL 5, f. 2, jioi id. Sby. 



P. niliersii, d'Orb., Am. Mer., p. 53, PL 4, f. 12-13. 



P. BoLiviENSis, d'Orb., Amer. Merid., p. 52, PL 4, f. 5-9. 



I refer a single rather imperfect specimen to this species, since it has all of the 



characters assigned by the author so far as can be made out. 



P. PAPiLio, n. s., PL 42, fig. 12, 12a. 



Shell subquadrate; beak small; cardinal line produced into two expanded sub- 

 mucronate points ; sides emarginate, narrowing below, base deeply emarginate ; 

 surface of large valve with a deep median, groove and two shallower radiating 



