i6 Bulletin 39 188 



Cardmm stiriahim Brown, Pilsbry Stormbus gatu7tensis Toula 

 Chione Roivelli Olsson Naiica Guppvaiia Toula 



Chione viach'opsis Conrad Turritella altilira Conrad and its 



Dosinla acetabulum Conrad varieties 



Comis molis Brown and Pilsbry 



The coralline phase is developed at several localities along 

 the coast, most important of which are Port Limon and Bocas 

 del Toro. Here the coralline limestones and associated marls 

 form the greater part of the Gattin section, but coralline rocks 

 ma}/- occur, interbedded with typical Gatun rocks, at any strati- 

 graphical level. 



These coralline limestones were formed, mainly as barrier 

 reefs some little distance from the old Gatun shore-line. Natur- 

 ally they offered very different habitat conditions from those of 

 the typical near-shore and often lacustrine Gatun. Hence we 

 find a fauna of deeper-water affinities with Pleurotomids and 

 thin-shelled Cones, as the most important and characteristic 

 element. In localities where these coralline rocks are exclusive- 

 ly developed, this fauna bears very little relation to the typical 

 Gatun fauna , although the two are contemporaneous. The 

 following are species of the coralline phase: 

 Peden corallLphila Olsson Mitra Alamagi-ensis var. 



Antig07ia Harrisiana Olsson coralliphila Olsson 



Gafrariuni limonensis Olsson Mitra poas Olsson 

 Large number of Pleurotomids Marginella avena Valennencies 

 Conus planiliratiis Sowerby Olivella limonensis Olsson 



Conus limo7iensis Olsson Phos elegans, variety limonensis 



Conus stenostomus Sowerby Olsson 



Turritella exoleta Linne Siliguaria modesta Dall, 



var. limonensis Olsson limonensis var. Olsson 



About 13 per cent, of the Gatun fauna is identical or closely 

 related to the recent species, the majority of which are found 

 living along the present Caribbean coast, certain others only on 

 the Pacific side in the Panama Province and a few common to 

 both. This large percentage of recent forms corresponds closely 



