Descriptions of New Species of Fossils from the Pliocene Clay Beds between Limon 

 and 3foen, Costa Rica, together ivith Notes on previously known Species from there 

 and elsewhere in the Caribbean Area. ^ \9,^1 



By Wm. M. Gabb. ^'^^ ^^^^^ 



I HAYE used this rather comprehensive heading for reasons similar to those 

 which prompted a like one for the Miocene fossils. Wherever no special locality 

 is mentioned, it must be understood that the clay beds of the Limon peninsula are 

 meant. Many species are quoted as living on the Cuban coast ; doubtless, when 

 the other islands shall have been as thoroughly studied, not only will the geogra- 

 phical range of these be increased, but many species now only known as fossils 

 will make their appearance. 



CRUSTACEA. 

 Crustacean remains are rare in this deposit, but I found one little nodule of 

 clay which disclosed the greater part of a small crab. On attempting to clean it, 

 it crumbled, all but the carapace and left hand, both of which are figured, slightly 

 magnified, on Plate 45, fig. 29, 



ATLANTA, Lesueur. 

 A. Ammonitiformis, Gabb, n, s., PI. 45, fig. 30. 



Shell very minute, dextral, spire well marked and slightly elevated. Dorsum 

 distinctly rounded in the young shell without trace of keel or angle ; becoming 

 angulated on the third volution, but bearing no keel or crest. Diameter, 1 mm. 



From the Moen beds. Most nearly allied to A. Peronii, but differs in the 

 lateral view of the side of the mouth. In that species the outline is a gentle, 

 regular curve; in this, it bends much more backwards towards the peripheral 

 margin, 



MUREX, Linn. 



M, EECURViROSTRis, Brod., p. Z. Soc, 1832, p, 174. •. 



M. nigrescens, Sby., P. Z. S., 1840, p, 138. 



Both the above names were given to shells found in the Pacific, and separated 

 on points which seem to be of too little value for specific distinction. Not only 

 am I convinced that our shell belongs to the species, but longer acquaintance with 



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