Heav;.'' shells of Antigona rTolticostata (Sov/erDjO as v/ell as the orsja£;e-colored 

 shells of I'acrocallista aur;mtlaca ( Souertiy) are ver;.- cormon on Taeaches. Both species 

 live iDelov: lo'rf-water nark on slightly nuddy bottoias. Ho live speciriens of these clans 

 are fotmd above low-vmter level. 



Among other clamsi the 'beautifully colored pink shells of Sanguinolaria telli- 

 noides A. Adans are ahundant, especially on the heaoh near Punta Pajaroa in the Gulf of 

 Chlrio_ul (station Zk) . Scallop shells were seen at almost every 'beachi they are repre- 

 sented by the following species; Pecten nodosus subnodosu s Sowerhy and Pec ten c irc-ularis 

 Sov/erhy. "o live scallotis were cau.^ht in the hand dredges. These mollusks, so highlj 

 esteemed for food in ITorth America, are ayoarently not eaten "oy the Panamanians. Cockles, 

 Cardium c onsors Broderip and Sowerhy, and other species not yet identified were freouently 

 encountered. Among other lanellibranchs, mention should he made of Cardita laticostata 

 Sov/erby, Codakia sp. . Chione crenifera (Sowerby) , Ch. undatella (Sowerby) , Ch. kelletti 

 (Hinds), Senele sp. , various snecies of Mactra and Pitar lupanaria lupanaria (Lesson) . 

 The shell of the latter mollusk has long sfil very fragile spines, which probably restrict 

 its movements greatly. The mollusk was found on extensive sand flats near Punta Pajaron 

 (Station 2U) . 



Most common .ssstropods on sandy flats are Terebra robusta Einus aiid Turritella sxi. 

 (probably T. tigrina Kiener) . 



Ajnong the many cone shells and other gastropods present on the beaches, the 

 follov/inff species were recorded: Conus purpurascens yirpurascens Broderip, C. archon 

 Broderir;, £. ferg-asonl Soverby, C^ dalli Stems, C. gladiator Broderip, Strombus gracilior 

 Gray (.juvenile forms), young Malea ringens (S\-;ainson) , various Turridae, Trona cervinetta 

 (Wiener) , Zonaria sp. , Zonaria arabicula (Lamark) , Z onaria annettae (Ball) , Cassis 

 eoarctatus Gray, Scaphander interrur)tus DaJ.1, Acmaea sp. , Aletes sp. , Crepedula sp. , and many 

 others v/hich could not be identified without more detailed study. 



On Coiba Island (Station 19), some of the sandy beaches were covered v;ith a thin 

 layer of very fine mud inhabited by millions of small Olivella , somewhat resembling 

 Olivella tergina T)uclos, but differing from it by its rather dark greenish color and simpler 

 nattern. The length of the mollusk varied from 5 to 10 mm. Larger forms, Oliva splendidula 

 Sovjerby and 0. splendidula fuscata , were found in the same environment, but v;ere less 

 aoundant. The shells of Olivella are used by the prisoners of the penal colony located on 

 the Island for making attractive ladies' bags (Fig. 21), curtains, and other objects. Due 

 to considerable variation in coloration and markings, the shells can be arranged in inter- 

 esting patterns. I estimate that more than 3500 small Olivella were used to make the bag 

 shovm in Pis- ?1. This occuTiation provides a small additional income to the prisoners, v;ho 

 sell their goods to the few visitors to the island. Shells of a fresh-water mollusk, 

 ITeritina latissima Broderip, are freouently found on beaches, especially in the vicinity of 

 fresh-water streams. 



In exploring the sandy beaches of Coiba Tsland, one freo^uently encovmters the 

 poisonous marine snake, Pelan:7drus platxirus . The snake is about 18 inches long, has a white 

 belly and black back, vrith. vertical marking; on the tail. When sv/imr.ing in v;ater, it can be 

 easily mistaken for an eel. Incidents of attacks by Pelamydrus platujus are rare. Although 

 the sea snakes are very noisonous and the potency of their venom exceeds that of cobra, 

 they are not aggressive, and when disturbed prefer to swim away. This beliavior is q.uite 

 opposite to that of the f er-de-lance ( Bothrops atrox) and the bushmaster ( Lachesis rauta) , 

 v;hich infest the forests and pastures on Coiba Island, and present a serious problem to the 

 persons clearing tropical jungles or working along the shores overgrown by vegetation. 

 Incidents of snake bites and ensuing death caused by the tvro most dangerous reptiles are 

 frequent. As a matter of fact, during my brief visit to the island (Pig. 22), two large 

 zebu bulls imported by the Government from India were killed by bushmasters. Hecords of the 

 local hosnital indicate that next to malaria v/hich prevails on the island (Simmons et al, 

 1939). the most numerous cases of hospitalization are those of snake bites?:?/ 



12/ Ihiring m:^ stay on Coiba Island, at the request of the local authorities, I collected v/ater 

 from two warm springs on the island and forv/arded the samples for chemical analysis to the 

 Geological Survey. The report of the Geological Survey is given at the end of the paper. 



33 



