GLOBIGERINIDAE-GLOBIGERINA.—ROTALIIDAE—SPIRILLINA. 37 
Family ROTALIIDE. 
Genus SPIRILLINA Ehrenberg, 1841. 
Spirillina vivipara Ehrenberg. 
(Plate 5, Figure 7.) 
Spirillina vivipara Ehrenberg, Abh. Akad. Wiss. Berlin, 1841, p. 442, plate 3, fig. 41.—Moe- 
bius, Beitr. Meeresfauna Insel Mauritius, 1880, p. 88, pl. 8, figs. 1, 2.—H. B. Brady, 
Rep. Voy. Challenger, Zoology, vol. 9, 1884, p. 630, pl. 85, figs. 1 to 5.—Flint, 
Rep. U.S. Nat. Mus., 1897 (1899), p. 326, pl. 71, fig. 4—Millett, Journ. Roy. Mier. 
Soc., 1903, p. 693.—Rhumbler, Zool. Jahrb., Abth. Syst., vol. 24, 1906, p. 32, 
pl. 2, fig. 7—Cushman, Bull. 71, U. S. Nat. Mus., pt. 5, 1915, p. 3, pl. 1, figs. 1, 2; 
fig. 1 (in text). 
Test typically free, rarely adherent, planospiral, coils of early portion in 
microspheric specimens at least narrow, those of later coils much wider and 
of nearly uniform width, faces somewhat flattened, but more often concave 
on both sides; sutures usually distinct and often considerably depressed; 
peripheral border rounded; wall marked by conspicuous perforations, ir- 
regularly scattered and most prominent on the last-formed volutions; 
aperture somewhat crescentic. 
Diameter of the Tortugas specimens 0.50 to 0.60 mm. 
Ehrenberg originally described this species from off the coast of 
Mexico, therefore in this same faunal region. His figure shows 4 
specimen with a single series of pores near the outer edge of the 
coil. Our specimens have the pores smaller and irregularly scattered, 
as shown (plate 5, fig. 7). In comparing d’Orbigny’s figures in 
the Cuban monograph, the reason for taking his Operculina incerta 
as the type of Ammodiscus incertus seems very questionable, the 
only thing in his description which would tend to seem like Am- 
modiscus being the single word “flavescente.” Except for this, it 
would seem that d’Orbigny might have had a Spirillina of the form 
here figured (plate 5, fig. 7). The measurements given by him, 
0.60 mm. (not 0.10 mm., as given by Brady), fits very closely this 
series of Tortugas specimens. Ammodiscus was not found at any of 
the Tortugas stations nor in the collection from the north coast of 
Jamaica, and I have not found it in shallow water from the coast of 
Florida or the Bahamas. A study of d’Orbigny’s type, if it is 
extant, should show whether or not his Operculina incerta really 
was Ammodiscus or whether it was a Spirillina. Until such exam- 
ination can be made it can not be definitely decided what should 
be the disposition of this d’Orbignyan species. The material from 
the West Indian and Floridian collections seems to be in favor of 
its being Spirillina. If this is true, the present species will have to 
be known as Spirillina incerta (d’Orbigny), and Ammodiscus will 
take its name probably from Williamson and be known as Am- 
modiscus arenacea (Williamson). 
Spirillina vivipara Ehrenberg var. 
(Plate 5, Figure 6.) 
There is a form of this species which, instead of the coarse, irreg- 
ularly scattered punctations, has them very numerous and arranged 
