566 
THE VOYAGE OF H.M.S.,. CHALLENGER. 
Fistulose form (PL LXXIII. fig. 17). 
Polymorphina lactea, var . fistulosa, Williamson, 1858, Rec. For. Gt. Br., p. 72, pL vi. fig. 150. 
„ „ var. tubulosa, Parker and Jones, 1862, Introd. Foram., App., p. 311. 
,, orhignii (pars), Brady, Parker, and Jones, 1870, Trans. Linn. Soc. Bond., vol. xxvii. 
p. 24d, pi. xlii. fig. 38, d. 
The test of this species is irregularly oval or oblong and much compressed, but it 
varies a good deal as to proportionate length and breadth. The segments are disposed in 
two, generally unequal, alternating series, and are marked externally by excavated sutures. 
The surface of the shell is smooth, in rare cases exhibiting a few faint longitudinal striae 
near the initial end. It sometimes attains a length of -g-th inch (3T5 mm.) or even more. 
In general terms Polymorphina compressa may be said to include the less regularly 
Textulariform varieties of the genus, its nearest allies being Polymorphina complanata, 
cTOrbigny, Polymorphina frondiformis, S. Y. Wood, and Polymorphina cylindroid.es, 
Roemer. Of these the first is distinguished by the exceedingly regular and equilateral 
Textidaria-like disposition of the segments, and Polymorphina frondiformis by its even 
larger dimensions and its surface-ornament of interrupted costae or tubercles ; whilst 
Polymorphina cylindroides has a long tapering test, less compressed than that of the 
present species and composed of a small number of nearly erect segments. 
Polymorphina comp)ressa is a cosmopolitan form, especially common in temperate 
latitudes ; nevertheless, it has been found as far north as lat. 79° 35' N., in Smith Sound, 
and at lat. 73° N. or thereabouts, on the shores of Novaya Zemlya. It is abundant in 
the temperate portion of the North Atlantic, preferring shallow-water margins, but 
extending sometimes to a depth of 400 or even 600 fathoms. In the tropical South 
Atlantic, and in the North and South Pacific, it is less frequent. 
It has been recognised as a fossil in the Lower and Middle Lias of the west and 
north of England (Brady, Blake) ; in the Lower Oolite, the Upper Oxford Clay, and the 
Kimmeridge Clay of England (Parker and Jones), in the Cretaceous system of England, 
France, Germany, and North America, and generally in the Tertiary and Post-tertiary 
formations of Europe. 
Polymorphina elegantissima, Parker and Jones (PI. LXXII. figs. 12-15). 
Polymorphina elegantissima, Parker and Jones, 1865, Phil. Trans., vol. civ. p. 438. 
„ „ Brady, Parker, and Jones, 1870, Trans. Linn. Soc. Lond., vol. xxvii. 
p. 231, pi. xl. fig. 15, a-c. 
The typical Polymorphina elegantissima differs from its congeners chiefly in the arrange- 
ment of the segments, the general plan of which is regularly biserial, but the alternation 
is inequilateral. The test consists of two alternating series of chambers, set obliquely to each 
other, in such away that on each face of the shell one series is hidden by the overlap of its 
