i6 



Bulletin 39 



188 



Cardium stiriatum Brown, Pilsbry Stormbus gatimensis Toula 

 Chiojie Roivelli Olsson Natica Gitppyana Toula 



Chione 'tnaciropsis Conrad Turritdla 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 Gatun section, but coralline rocks 

 may occur, interbedded with typical Gatun rocks, at an}' strati- 

 graphical level. 



These coralline limestones w^ere formed, mainl}^ 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 ver}^ little relation to the typical 

 Gatun fauna , although the two are contemporaneous. The 

 following are species of the coralline phase: 

 Peden coralUphila Olsson Mitra Alamagrensis var. 



Antigona Hari^isiayia Olsson coralUphila Olsson 



Gafrarium Ihnonensis Olsson Mitra poas Olsson 

 Large number of Pleurotomids Marginella avena Valennencies 

 Conus planiliratus Sowerby Olivella limoneiisis Olsson 

 Conus limoiiensis Olsson Phos elegans^ variety limo7iensis 



Conus stenostomus Sowerby Olsson 

 Turritella exoleta Ivinne Siliquaria 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 



