GLOBIGERINIDAE-GLOBIGERINA. — ROTALIIDAE — SPIRILLINA. 37 



Family ROTALIID^. 



Genus SPIRILLINA Ehrenberg, 1841. 



Spirillina vivipara Ehrenberg. 



(Plate 5, Figure 7.) 



Spirillina vivipara Ehrenberg, Abh. Akad. Wiss. BerUn, 1841, p. 442, plate 3, fig. 41. — Moe- 

 bius, Beitr. Meeresfauna Insel Mauritius, 1880, p. 88, pi. 8, figs. 1, 2.— H. B. Brady, 

 Rep. Voy. Challenger, Zoology, vol. 9, 1884, p. 630, pi. 85, figs. 1 to 5.— Flint, 

 Rep. U. S. Nat. Mus., 1897 (1899), p. 326, pi. 71, fig. 4— Millett, Journ. Roy. Micr. 

 Soc, 1903, p. 693.— Rhumbler, Zool. Jahrb., Abth. Syst., vol. 24, 1906. p. 32, 

 pi. 2, fig. 7.— Cushman, Bull. 71, U. S. Nat. Mus., pt. 5, 1915. p. 3, pi. 1, figs. 1. 2; 

 fig. 1 (in text). 



Test typically free, rarely adherent, planospiral, coils of early portion in 

 niicrospheric 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- 

 regiUarly 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 a 

 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 



