I09 MoivIwUSCA OF THE GULF OF MEXICO 77 



Tex. Pleistocene : New Orleans well of 1856, 41 feet, 

 Lake Borgne borings, Grand Chenier, Knapp's wells, Ter- 

 rebonne Parish, No. 2 at 1050-iigo, 1542- 1632, 1791- 

 1839, No. 3 at 570-700, 1400-1550 feet. Upper Miocene: 

 Galveston deep well at 2236-2600 feet (Harris). 

 Note. — It was from the violet margins of l\ mercenaria that 

 the Indians of the East coast made the discs of pur])le 

 wampum which was more costly than the white. 

 campechiensis Gmelin, Sj-st. Nat. 5, p. 3287, 1792 ; Dall, Tr. W. 

 I. S., 3, p. 1 315, 1903 ; Vaughan, Publ. 134, Cam. Inst., 

 p. 171, 1 9 10. 

 prceparca Say, 1822 ; niortoni Conrad, 1837 ; Holmes, Post- 

 Pi. F. S. C, p. 34, pi. 6, f. 12, 1858 ; calcarea Philippi, 

 1844; temiilamellata Sowerby, 1853; alboradiata Sower- 

 by, 1853, Reeve, Conch. Icon., pi. 3, f. 7, 1863 ; tetrica 

 Conrad, 1838 ; per magna Conrad, 1838, Tuomey and 

 Holmes, Pleio. Fos. S. C, p. 86, pi. 22, f. 2, 1856 ; capax 

 Conrad, 1863 ; siibmorioni d'Orbigny, 1852 ; obiusa, '66, 

 ciineata, '68, and caroli7iensis, '75, Conrad. 

 Distribution. — Chesapeake Bay to Yucatan, moderate depths. 

 Miocene to Recent. Gulf coast. — Recent : Indian Pass, 

 Crooked Isl., Cedar Keys, Fla. ; Horn Isl., Miss. ; Cam- 

 eron, Chandeleurs, La. ; Corpus Christi, Alligator Head 

 (dredged). Pass Cabello, Matagorda Baj' (immense shells, 

 Mitchell), Galveston, Texas. Dall has named the Texan 

 form var. texana. Pleistocene : Labelle and Ospre\', 

 West Fla. Pliocene : Shell Creek, Fla. 



Genus GEMMA Deshayes 

 gemma Totten, var. purpurea H. C. Lea, Am. Jour. Sci., p. 106, 

 pi. I, f. I, 1842, (as Cyreiia); Dall, Tr. W. I. S., 3, pi. 24, 

 f. 2, 4, 4 b, 1898 ; p. 1332, 1903 ; Vanatta, Proc. A. N. S. 

 Phila., 55, p. 757, '03 ; Johnson, Occ. Papers, Bost. See. 

 N. H., 7, p. 71, 1915. 

 Parastarte conccntrica Dall. Bull. 37, U. S. N. M., jx 48, 



1889, Nomeyi midiim. 

 f manhattanensis Prime, Jay's Cat., 4th ed., Suppl., p. 466, 



