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THE VOYAGE OF H.M.S. CHALLENGER. 
Fistulose form (PI. LXXIII. fig. 14). 
“Polymorpha Corcula Spinosa,” Soldani, 1791, Testaceographia, vol. i. pt. 2, p. 114, pi. cix. 
fig. I., &c. 
Misilus aquatifer, Montfort, 1808, Conch. System., vol. i. p. 294, 74 e genre. 
Apiopterina d’Orbigni, Zborzewski, 1834, Nouv. Mem. Soc. Imp. Nat. Moscou, vol. iii. p. 311, 
pi. xxviii. fig. 2, b. 
The typical Polymorphina lactea has an ovate or subpyriform, nearly symmetrical 
test, almost circular in transverse section, and with about four visible chambers ; the 
chambers are elongate, and are set in an erect or somewhat oblique manner, and their 
sutures are slightly excavated externally. Such forms merge by insensible degrees into 
the globular Polymorphina gibha, on the one hand, and into the Pyruline type, 
Polymorphina gutta, on the other. Of the drawings, fig. 1 1 represents a typical specimen, 
corresponding accurately with Walker’s original sketch; whilst fig. 14 (PI. LXXI.) is an 
elongate individual that might almost be assigned to Pyrulina gutta, d’Orbigny (Ann. 
Sci. Nat., vol. vii. p. 267, pi. xii. figs. 5, 6 ; — Modele, No. 30), and only differs from 
Globulina minuta, Roemer (see Reuss’s figure, Denkschr. d. k. Akad. Wiss. Wien., vol. i. 
p. viii. fig. 8), by the absence of any lateral compression. 
Polymorphina lactea is found to a greater or less extent in almost every sea, but it is 
most abundant and the specimens are better developed in comparatively shallow water 
and in temperate latitudes. In the North Atlantic the species has not been met with at 
a greater depth than about 400 fathoms, but in the South Atlantic it has been observed 
as low as 1990 fathoms, in the North Pacific at 2300 fathoms, and in the South Pacific at 
2350 fathoms ; but in all cases in which it occurs at great depths the specimens are rare and 
individually of exceedingly small size. Its area of distribution extends as far north as the 
shores of Novaya Zemlya, about lat. 73° N., whilst in the opposite hemisphere the Cape 
of Good Hope appears to be about its southern limit. 
The first appearance of the species as a fossil is probably in beds of Jurassic age, 
namely, in the Kimmeridge Clay and the Upper Portland Limestone of the south of 
England (Parker and Jones). It occurs in the Cretaceous system of Bohemia and Russia, 
in the Lower and Middle Tertiaries of Northern and Central Germany and of England, in 
the Subapennine deposits of Italy, in the Crag of the eastern counties of England, and 
in the Post-tertiary formations of Scotland, Ireland, Norway, and Canada. 
Polymorphina amygdaloides, Reuss (PL LXXI. fig. 13). 
Globulina amygdaloides, (?) Reuss, 1851, Zeitschr. d. deutsch. geol. Gesellsch., vol. iii. p. 82, 
pi. vi. fig. 47. 
Polymorphina amygdaloides, Id. 1855, Sitzungsb. d. k. Akad. Wiss. Wien, vol. xviii. p. 250, 
1. viii. fig. 84. 
