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60 1 



TERTIARY FAUNA OF FLORIDA 



P. Scgitcnza- Dall, from the Astiano division of the Calabrian Pliocene, was 

 sent to Dr. Jeffreys under the name of P. vva/is, and I suppose is the shell so 

 catalogued by Seguenza in his Tert. Fos. of Reggio. It is much larger 

 even than /'. militirix, and has the ligamentary fossette somewhat gaping; 

 eight teeth, of which five are posterior, and all are much crowded. The inner 

 edge of the hinge-plate is excavated behind the anterior teeth, and the width 

 of the cardinal border at the lateral teeth is less, proportionally, than in the 

 other species. 



P. Adauisi Dall (plate 24, figure 9) was dredged seven miles east of 

 Fowey Rocks, Straits of Florida, by Dr. W. H. Rush. It is proportionally 

 shorter and wider than the other species. It has three squarish high anterior 

 cardinal teeth and two stout conical posterior teeth in the right valve, perhaps 

 three in the other. There is a well marked small shelf between the posterior 

 teeth and the outer cardinal border, and no groove on the other side. The 

 exterior is smooth and covered with a pale yellowish epidermis ; the interior 

 is glassy rather than nacreous. It is figured on the same scale as P. Woodii. 

 The posterior wing of the cardinal border is wider than in any of the other 

 species. 



The reader will understand that all these notes are taken from authentic 

 specimens and not from figures. 



Subgenus CYRILLA A. Adams. 



Ihtxleyia A. Adams, Ann. Mag. Nat. Hist., 3d Ser., v., p. 303, April 1860. Type H. 



sulcata A. Adams (not Huxlcyia Bowerbank). 

 Cyrilla A. Adams, Ann. Mag. Nat. Hist., 3d Ser., v., p. 477, June, 1860; ix., p. 295, 



1862. Journ. de Conchyl., xvi., p. 41, 1868. 



In this division of the group the fossette for the ligament has been en- 

 larged and rounded. The space occupied by the anterior cardinal teeth in 

 typical Plcimxlon has been so encroached upon that these teeth have been 

 more or less absorbed or never developed, while the posterior cardinal teeth, 

 upon which more would depend after the others were gone, have become 

 wider and stronger and extend from the inner to the outer margin of the 

 cardinal plate, being somewhat wedge-shaped in section or wider at the inner 

 edge. In Cyrilla sulcata there are six cardinal teeth in the left valve. Of 

 these, one, or possibly two, may have been originally part of the anterior 

 series. All have been more or less modified into closer uniformity with the 

 true posterior series ; they no longer form an angle with one another, and the 



