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TERTIARY FAUNA OF FLORIDA 



Mactra crassidciis Conr., Medial Tert., p. 69, pi. xxxix, fig. 5, 1S40; Am. Journ. Sci., 



xli., p. 347, pi. 2, fig. II, 1 84 1. 

 Mactra triqiieira Conr., Medial Tert., p. 69, pi. xxxix., fig. 3, 1840; Proc. Acad. Nat. 



Sci. Phila., i., p. 324, 1843. 

 Mactra {Spisuhi) trigonalis Conr., MS. 



Hemimactra congcsta Conr., Proc. Acad. Nat. Sci., 1862, p. 572, 1863. 

 Miilinia crassidcns ef triquctra Conr., ibid., p. 573. 

 Standella congcsta Conr., ibid., p. 573. 



Chesapeake Miocene of Maryland, Virginia, the Carolinas, and of Florida 

 at Alum Bluff (upper bed), De Leon Springs, and other localities near Talla- 

 hassee and along the Chipola River ; Pliocene of the Croatan beds, North 

 Carolina, and some localities in South Carolina. 



This well-known and variable species is of wide distribution. Short, 

 high specimens form the variety triquetra of which crassidcns is a young shell. 

 Conrad, by the extraordinary carelessness which was normal to him, placed 

 the two latter names under Mitlinia, while congcsta appears both as Hemi- 

 mactra and as Standella in different places in the same list of Miocene fossils 

 printed in 1863 ! 



Mulinia lateralis Say. 



Mactra lateralis Say, Journ. Acad. Nat. Sci. Pliila., ii., p. 309, 1821. 



Mactra rostrata Phil., Abbild. und Besclir., iii., p. 138, pi. 3, fig. 6, 1845 ; not of Spengler, 



1802. 

 Mactra corbuloidcs (Deshayes), P. Z. S., 1854, p. 63 ; Reeve, Conch. Icon., Mactt-a, fig. 



103, 1854. 

 Standella lateralis Conr., Proc. Acad. Nat. Sci. Phila. 1862, p. 573, 1863. 

 Mulinea lateralis Conr., Am. Journ. Conch., iii., Suppl., p. 31, 1868. 



Chesapeake Miocene of Duplin County, North Carolina, and the Pasca- 

 goula clays of Mississippi ; Pliocene of the Waccamaw beds of South Caro- 

 hna, the Caloosahatchie River and Shell Creek in Florida ; the Pleistocene 

 from Maine to Texas, and the recent fauna from Massachusetts Bay south- 

 ward. 



This species shows the same variations in form as the preceding. The 

 shells are smoother and less rude in the southern portion of their range, and 

 the variety corbuloidcs is relatively more abundant in the south, but may be 

 found represented wherever the species is distributed! It bears to the typical 

 form a relation analogous to that which M. trignctra bears to the typical M. 

 congcsta or Spisiila Ravcncli to 6". siniilis Say. 



