300 ]\Ir. J. Orfon on the Evidence of 



for other localities. In Febniary 1870 he reported a large 

 deposit on tlie south side of the Maranon, thirty miles below 

 Pebas, at Pichaua, just west of Cochaquinas *. The shells 

 Avere larger and more plentiful than at Pebas, but were found 

 in the same layers of red and blue elays, from six to twenty 

 feet beneath the soil. A collection (in quantity about half a 

 busliel) was received in August, and submitted to the eminent 

 ])alfeontologist, T. A. Conrad, Esq. His paper, published in 

 the 'American Journal of Conchology,' Oct. 10, contained 

 many additional species, and corrected some mistakes into 

 which Mr. Gabb had fallen from lack of perfect specimens. 

 The following is a complete list, 'numbered in the order of 

 abundance. No. 1 being the most numerous f: — 



The Neritina^ which Gabb made identical with the living 

 N. 2}up(i'} proves to be a new species. The If>(ra Ortuni is 

 aecom])anied by an immense number of small, delicate shells, 

 which Conrad considers its young. He thinks the genus is 

 related to Tricula. Liris and Dyris probably belong to the 

 Melaniidce ; and Ehora is presumed to be a freshwater genus. 

 Of Hemisinus and Bidimus there was but one specimen each. 

 PacJn/donX is the most important genus, the collection fur- 

 nishing seven distinct species. Conrad makes it one of the 

 C()rl)ulidiu, though its s})iral beaks are in marked contrast 

 with those of Corlnda. Some of the species attained con- 



* Mr. Ilauxwoll writes tbat he has found similar shell-beds on the 

 north side of the Maranon, about a mile inland, both east and west of 

 Pebas, and also at Maucallacta. 



t The type series is now in tlio Xew-York State Geoloirical cabinet. 



\ As this name is too near Pachi/odon, Conrad sup-gests Am;>ofhi/ris. 

 It had an internal cartilage in a pit behind the tooth of the riirht valve, 

 exactly as in Corhitla : and Meek is inclined to consider them identical. 

 'l'li(> only sliell observed by Darwin in the Pampean formation was Azara 

 hdiiata, D'Orb., one of the livinjr Corhulida\ It has no spiral Ivak. 

 t^everal species oi Azara {Vatanwmya) live in the brackish parts of the 

 Amazon. Corhulcp were abundant in the earlv Tertiarv. See Ann. Nat. 

 Hist, for .fan. and Feb. 1871. 



