372 



BULLETIN 100, UNITED STATES NATIOIsrAL MUSEUM. 



AMPHISTEGINA LESSONII d'Orbigny, var. MADAGASCARIENSIS d'Orbigny. 



Amphistegina madagascariensis d'Orbigny, Ann. Sci. Nat., vol. 7, 1826, p. 305, 

 No. 5.— FoRNASiNi, Rend. Acad. Sci. Bologna, vol. 7, ]903, p. 144, pi. 2, fig. 

 5. — Heron-Allen and Earland, Trans. Zool. Soc. London, vol. 20, 1915, 

 p. 736. 



This form, wliich is here referred to d'Orbigny's Ainphistegina 

 raadagascariensis , seems to be very distinct in the Philippine material 

 and may be a vaUd species. It differs from the typical A. lessonii 

 in the smaller number of chambers and the acutely carinate pe- 

 riphery, the unequal biconvex form, and the larger umbonal clear 

 space. The sutures are more evenly curved and are usually de- 

 pressed. In the Philippine material there seem to be no intermediate 

 forms between these two. This variety is found under similar con- 

 ditions as the typical, most abundant in warm shallow waters, and 

 occurs with the typical, although in less numbers. 



Amphistegina lessonii, var. madagascariensis — Material examined. 



AMPHISTEGINA LESSONII d'Orbigny, var. RADIATA (Fichtel and Moll). 



Nautilus radiatus Fichtel and Moll, Test. Micr., 1798, p. 58, pi. 8, figs. 8, a-d. 

 Amphistegina radiata Chapman, Proc. Zool. Soc. London, 1895, pp. 45-47, pi. 1, 



figs. 8-10, 12. 

 Amphistegina lessonii, var. radiata Heuon-Allen and Earland, Trans. Zool. 



Soc. London, vol. 20, 1915, p. 736. 



This large, many-chambered, biconvex form, which is distinguished 

 by Chapman and also by Heron- Allen and Earland, is common at some 

 of the stations. It is characterized by the straight, radiating suture 

 lines which appear as transparent lines in the material of the test. 



