

96 CONTRIBUTION TO THE PALEONTOLOGY OF TRINIDAD. 



limestone near its base along the Chattahoochee River. Other Midway localities 

 where more or less typical forms have been obtained are in Texas near Kemp, 

 Kaufman County, and in Arkansas near Little Rock. The species also occurs in 

 Tennessee (Middleton), Alabama, and Mississippi; and later Professor Harris 

 adds that the shell presents a great many varietal forms in the Lignitic, and 

 finally merges through the variety postmortem Harris into T. carinata of the 



Claiborne Eocene. 



Such being its distribution on the North American continent we will now 

 trace it as far as known in the South American region. 



In 1887 Dr. White described Turritella sylviana (which is specifically identical 

 with mortoni) from the Rio Maria Farinha beds in the State of Pernambuco, 

 Brazil. The figures are very like the Soldado shells both in form and size. It 

 appears as if T. mortoni in the far south had become smaller ; or else all found so 

 far have been young individuals. 



The shells from Soldado Rock, Bed No. 2, are in every respect remarkably 

 close to Conrad's type. They show the sharp carination of the lower part of 

 each whorl which gives a slightly overhanging effect, and the tendency, like the 

 type, to three prominent raised lines near the base of the whorls. They differ 

 only in being smaller. 



Length of shell figured approximately 16}^ mm., breadth of last volution 6 

 mm. This is close to the Pernambuco shells which measured about 18 by 6J/£ 

 mm. 



Locality. — Bed No. 2, Soldado Rock, Gulf of Paria. 



Geological horizon. — Midway Eocene. Equivalent to the Midway of Alabama 

 and of the Maria Farinha beds, Pernambuco, Brazil. 



History of the genus. — It is a singular fact that the genus Turritella, which 

 began in the Cretaceous, and is so very abundantly represented in the American 

 Tertiaries, in which more than eighty species have been named, should be rare 

 in our seas of to-day. Very few species and individuals are now found, especially 

 on the Atlantic coast of the Americas. 



*■ 



Turritella mortoni Conrad var. Plate XII, Figure 24. 



Remarks.— A number of specimens of a Turritella were found in the Lignitic 

 fauna of Soldado. 



They are probably a varietal form of T. mortoni Conrad. 

 Locality— Bed No. 8, Soldado Rock, Gulf of Paria. 

 Geological horizon. — Lignitic Eocene. 



Turritella 



Figu 



Description.— Shell small, slender, number of whorls not known; sculpture 

 on each volution consisting of three primary spiral ridges; of which the one 

 directly above the suture is by far the most prominent ; and of very faint inter- 

 mediate spiral threads, only visible with a lens. The lowest basal revolving 

 ridges have a slightly beaded aspect which may be due to erosion. 



