30 AXEL A. OLSSON 



common one is Aequipecten circularis which shows a wide range of colora- 

 tion. A. purpuratus, so common in Peruvian waters, has been recorded on 

 good authority from Panama and elsewhere but is rare, and its distribution 

 irregular. Pecten vogdesi, although first described under the name P. denta- 

 tus, presumably from Santa Elena, Ecuador, appears to be largely restricted 

 to the Gulf of California. Like the Pectens, the oysters are relatively unim- 

 portant in the faunal makeup, although some interesting species are repre- 

 sented. Amongst them is Ostrea iridescens, a purely marine form which 

 sometimes grows to a large size. It is much sought for by the natives, but 

 its flavor is strong, probably due to a high iodine content. Another purely 

 marine species is the Ostrea jischeri, a pycnodonta, with a peculiar, porous, 

 or honey-combed texture, relatively rare but widely distributed through 

 the whole faunal province. The smaller 0. columbiensis is often seen in the 

 markets of Ecuador. The most interesting of the Anomiidae is the large 

 Placuanomia cumingii, similar to the P. plicata of the Miocene of the 

 Carolinas. As presently interpreted, Spondylus appears to have three species 

 in the Panamic fauna but the distinctions between them are ill-defined due 

 to incomplete data and the great variability of its characters due to fixa- 

 tion. In contrast with the Caribbean fauna, the Lucinidae are poorly repre- 

 sented in the Pacific zone either in the Recent or fossil state. Codakia has 

 two fine species but both rare. C. distinquenda attains a much larger size 

 than any species of the genus is the Caribbean. Of unusual interest is 

 D. punctata, an Indo-Pacific species recorded from the Pearl Islands and 

 from the Galapagos. There are two species of Afwdontia, but they are rare 

 and have been seldom collected. Amongst the Crassatellidae and Carditidae 

 are several fine species which give color and character to the Panamic 

 fauna. Eucrassatella gibbosa, with its coarse, heavy shell, is common at some 

 localities. Cardita tricolor is the commonest member of its family and shows 

 a wide range of coloration. Conspicuous because of their large size are the 

 relatively rare C. cuvieri and C. megastrophia. There are two species 

 of Carditamera. C. radiata, largely restricted to Panama, is a form closely 

 related to C. arata of the East Coast or Atlantic Miocene. As in most warm 

 water or tropical faunas, the Tellinidae are represented by a large number 

 of species, and other new ones will no doubt be discovered with further 

 exploration. Some of these tellinids are brightly colored, as for instance, 

 those belonging to the genus Tellinidella. Conspicuous in the fauna are the 

 several species of Fhrimetis and especially the numerous forms of Eurytellina. 

 Of special interest is Psammothalia cognata, a species fairly common in 

 Panama and extending to Peru, nevertheless, it has remained rare in most 

 collections; a few years ago, specimens were obtained in dredgings off the 

 gulf coast of Spanish Honduras which appeared to be identical with typical 

 P. cognata from the Pacific Ocean. To the Donacidae belong some of the 

 finest species of the family; Iphigema altior, found in more or less brackish- 

 water situations, is closely allied to the West Atlantic /. brasUiana; several 

 species of Donax, common on sandy beaches such as D. asper, D. peruviana, 

 and D. panamensis, are current items of food amongst the native population; 



