52 THE NAUTILUS. 



Senegambian specimens I find the hinge quite different from Joannis' 

 figure, and essentially similar to that of American species. 



The first of the latter was described by Morelet in 1851, from 

 Porto Rico, under the name of C. americana. It differs from the 

 African species by its smaller and more delicate shell, its more 

 quadrate form and proportionately shorter ligament. Some species 

 reported from the Philippines by Sowerby I have shown to have a 

 different hinge and separated under the name of JoannisieUa. 



The first continental American species was obtained by Hemphill 

 in the marshes of southwest Florida (Marco, Boca C'eiga Key, and 

 the Everglades) where it affects brackish, or even tolerably salt 

 water, indifferently. This I named in manuscript C.floridutia (cf. 

 Bull. 37, U. S. Nat. Mus., 1889, No. 217, p. 50). 'Lastly a fine 

 Pliocene species was obtained by Mr. Willcox and myself from the 

 marls of the Caloosahatchie River in south Florida. 



Diagnoses of the two latter follow. 

 Cyrenoidea floridana (Dall, MS.. 18SH) n. s. 



Shell rounded, small, thin, very delicate, whitish or translucent 

 with a pale, silky, yellowish, dehiscent epidermis ; surface smooth, 

 or sculptured only by incremental lines; interior margin smooth, 

 polished ; the visceral area with a dull, more or less punctate sur- 

 face ; pallial line indistinct, often broken, not sinuous; ligament 

 short, brownish, external ; hinge as in C. diiponti but more delicate. 

 Largest specimen, Ion. 13'5, alt. 12'5, diameter S'O. 



The range of the species, as far as known, is from Brunswick 

 Georgia, south to the Everglades on the east, and, on the west, north 

 to Charlotte Harbor and vicinity. 



The animal is distinctly Lucinoid, the foot is long, slender, filiform 

 and with an ovate, swollen distal termination. 

 Cyrenoidea oaloosaensis n. s. 



Shell large, thin, resembling C. (itn-liJinia, but coarser, with ruder 

 concentric sculpture, sometimes approaching undulations; more in- 

 equilateral, the anterior part relatively smaller and shorter, the 

 anterior left bifid cardinal tooth proportionately much shorter than 

 in cither of the other species of the genus. Lou. of shell 30'9, alt. 

 27'0, diameter 17'5 mm. 



The shell is known, so far, only from the Pliocene marls of south 

 Florida. 



All the species are very similar to one another, and differ only in 

 minor details of form and hinge. They would, as a rule, be taken 

 for Diplodoutas except for the differences of the hinge. 



