FOKAMINIFERA OF THE ATLANTIC OCEAN 



79 



ary canal system developed; aperture small, ventral, the wall granular 

 about the opening. 



Tertiary to Recent. 



In the more primitive species of the genus the transition from 

 Asterigerina may be seen, and the test is comparatively simple. In 

 the larger, more complex species the test becomes somewhat involute 

 and the earlier stages are not visible. The genus is characteristic of 

 coral reef conditions of the Tropics developing most highly in the 

 Indo-Pacific. In various parts of the Tertiary it was often very 

 abundant as it is today in its selected habitat. 



AMPmSTEGINA LESSOND d'Orbigny 



Plate 16, figures 1-3 



Amphistegina lessonii d'Orbigny, Ann. Sci. Nat., vol. 7, 182G, p. 304, No. 3, 

 pi. 17, figs. 1-4 {Quoit iu description of plate); Modeles, No. 98, 1826. 



Amphistegina gibbosa d'Okbigny, in De la Sagra, Hist. Fis. Pol. Nat. Cuba, 

 1839, "Foraminiferes," p. 120, pi. 8, figs. 1-3. 



No attempt is made here to give complete references to this species 

 as there are several species and varieties in the present oceans espe- 

 cialljT^ in the Indo-Paciiic. d'Orbignj- gave the name gibbosa to his 

 West Indian material but with rather large suites of specimens I have 

 been unable to separate this from the Pacific form. The West 

 Indian form is relatively small, not usually exceeding 2 millimeters 

 and usually smaller. The structure is relatively simple and there is 

 an umbo on both sides while the sutures are not complex. The 

 figures will show well the characters of the West Indian form. It 

 occurs typically in the shallow water of coral reef areas. It was 

 abundant at the Tortugas, on the north coast of Jamaica, coasts of 

 Cuba and Porto Rico. 



Amphistegina lessonii — Material examined 



station 



Locality 



Depth 

 in 



fathoms 



Bot- 

 tom 

 tem- 

 pera- 

 ture 



Character of 

 bottom 



Abundance 



Albatross 



D2.315...] 24 26 00 N.; 81 48 15 W. 



D2317..J 24 25 45 N.; 81 46 45 W. 



D2318... 24 25 45 N.; 81 4G 00 W. 



D2352... 22 35 00 N.; 84 23 00 W. 



D23.58... 20 19 00 N.; 87 03 30 W. 



D2.371... 29 17 00 N.; 85 30 45 W. 



[D2388...i 29 24 ,30 N.; 88 01 00 W. 



D2629...' 23 48 40 N.; 75 10 40 W. 

 D2n39... 25 04 50 N.; 80 15 10 W. 

 D2755..J 3 22 00 S.; 37 49 00 W. 

 D2758...! 6 59 00 S.; 34 47 00 W. 



6 ; Dry Tortugas, Fla 



8 do 



9 do — 



.do. 

 .do. 



.do. 



37 



45 



45 



463 



222 



26 



35 



1169 



56 



417 



20 



1 



1 



I 



40.5 

 79 



- C. 

 23.2 

 23 



CO 



CO 



CO 



wh. CO 



fne. wh. co.- 

 gy..';.,brk.sh. 



yls., bk. sp.. 



co.s 



co.s 



gy. sp. spk.- 



brk. sh 



m. 



m 



m 



s 



hrd 



fne. s 



Abundant. 

 Rare. 

 Common. 

 Rare. 

 Do. 

 Few. 



Common. 



Rare. 



Common. 



Few. 



Do. 



Do. 



Do. 

 Common. 



Rare. 

 Abundant. 



Do. 



