TROPICAL PACIFIC FORAMINIFERA OF "ALBATROSS" 67 



waves and currents. In the shallow-water collections it has occurred 

 at the following stations in shoal water; Pinaki Atoll, Paumotu 

 Islands, abundant on the beaches and inside the lagoon; Hereheretue 

 Atoll, Paumotu Islands, beach off wharf; Makemo Lagoon, Paumotu 

 Islands; Apataki, Paumotu Islands; Rutavu; Rongelap Atoll, Mar- 

 shall Islands; Vavau Anchorage, Tonga Islands; 40-50 fathoms, Fiji; 

 Port Lotten, Kersail, Caroline Islands; and Aloji Nine. From the 

 deeper-water Albatross stations the species has occurred as shown in 

 Table 32. 



Genus MARGINOPORA Blainville, 1830 



Marginopora Blainville, Diet. Sci. Nat., vol. 60, p. 377, 1830 (Quoy and 



Gaimard, MS.); Man. Actin., p. 412, 1834. 

 Synonym: Orbitolites (part) of authors (not Lamarck). 



Genoholotype. — Marginopora vertebralis Blainville. 



Test in the early stages similar to Sorites with one or two rows of 

 apertures, later vdth the two original planes of chambers forced apart 

 and filled with a high series of chamberlets, those adjacent to each 

 annular chamber connecting, the outer wall projecting beyond the 

 peripheral plane of the lateral chambers; the apertures in more or less 

 vertical rows on the periphery with a horizontal row above and below. 

 Recent. 



MARGINOPORA VERTEBRAUS Blainville 



Plate 19, Figures 11, 12 



It is difficult to determine this species. There seem to be two dis- 

 tinct forms developed in the South Pacific, one of which attains a 

 size of usually not more than 3 mm, having the central portion very 

 much depressed and the periphery thickened. This form is abundant 

 and widely distributed in shallow water, our specimens representing 

 the following localities: Hereheretue Atoll, Paumotu Islands; Pinaki 

 Atoll, Paumotu Islands; Apataki Atoll, Paumotu Islands; Makemo 

 Lagoon, Paumotu Islands; Rutavu; 12 fathoms off Nairai, Fiji; and 

 Mokaujar Anchorage, Fiji. There are also specimens from the 

 Albatross deeper-water stations, mostly either worn or very small 

 specimens. 



The other form is a much larger and flatter one, the center being 

 only slightly depressed, and attaining a diameter of nearly 10 mm. 

 Tliis larger form was found only at Mokaujar Anchorage, Fiji, where it 

 was very abundant. A further study of these may show that the two 

 forms are not closely related. 



