998 MESSRS. BRADY, PARKER, AND JONES 
? Polymorphina ovula, Terquem (in part), 1864, 4"* Mém. Foram. Lias,, p. 294, pl. 11. figs. 35 Se. 
P. angustata, id. ibid. p. 296, pl. 12. figs. 33, 34. 
P} sinuata; id. ibid. p. 298, pl. 12. fig, 48. 
compressa, Brady, 1864, Trans. Linn. Soc. Lond. vol. xxiv. p. 473; Brady, 1865, Nat. Hist. Trans. 
Northumberland & Durham, vol. i. p. 99. 
sacculus, Stache, 1865, Novara-Reise, vol. i. 2% Abtheil., Paläont. Neu-Seeland, p. 259, pl. 24. fig. 6. 
incavata, id. ibid. p. 260, pl. 24. fig. 7. 
compressa, Jones, Parker, and Brady, 1866, Monog. Crag Foram. pl. 1. figs. 54, 65, 7 7—80. 
Zeuchneri, Reuss, 1867, Sitzungsb. k. Akad. Wissensch. vol. lv. p. 74, pl. 4. fig. 1. 
ovata, id. ibid. p. 75. 
compressa, Brady, 1867, Proc. Somerset. Arch. Soc. vol. viii. p. 114, pl. 3. fig. 50; Sars, 1868, 
Vidensk.-Selsk. Forhandlinger for 1868, p. 248; Karrer, 1868, Sitzungsb. k. Akad. Wissensch. 
vol. lviii. p. 174. 
P. acuta, Karrer. ibid. p. 174. 
P. compressa, Brady, 1868, in Crosskey & Robertson's Memoir, Trans .Geol. Soc. Glasgow, vol. iii. ps. 118. 
Polymorphina, sp., Von Schlicht, 1869, Foram. Septar. Pietzpulil, nos. 495. & 496, pl. 32. figs. 29-32 E 
35-38. 
Characters.—Shell oblong, inequilateral, compressed, more or less fusiform. Chambers 
numerous, arranged in two unequal series, somewhat. inflated. Septal lines depressed. 
Surface smooth. Aperture variable, MT simple, cireular, and. coronate, sometimes 
labyrinthic or porous. Length 3 to yo inch. 
The three figures of the exterior aspect of Pojiksi compressa (Plate XL. 
figs. 12, a, b, c), although they indicate a considerable range of variation, from the wide out- 
spread examples like those found in the Crag to the tapering specimens separated by 
D'Orbigny under the name P. acuta, fall far within what may fairly be regarded as the 
limits of the present group; for, on the one hand, its modifications may be said to lose 
themselves amongst the less regular examples of P. complanata, whilst, on the other, they 
are scarcely separable from the feebler forms typified by P: fusiformis and. P. cylindroides. 
A somewhat indefinite biserial arrangement, in which the segments appear irregularly 
opposed to each other rather than in alternation, together with the rounded margins and 
constricted septa, are characters sufficient’ for general diagnosis. The difficulty in dis- 
tinguishing attenuated specimens from those of P. cylindroides is confessedly great ; but 
the less compressed contour of the latter, its few chambers, and their erect position will 
usually serve the purposes of the systematist. 
- So far as it is in our power to determine, from the information supplied by the respec- 
tive authors, the representatives of all the reputed species comprised in the foregoing ex- 
tended synonymy answer to the characters assigned to this subtype. We reserve our 
judgment in respect to those taken from the works of Prof. Ehrenberg and M. Terquem, 
for reasons already given. 
Distribution.—In Polymorphina compressa we have one of the commonest and one 
of the most widely spread members of the genus.. Setting aside the Silurian casts 
figured by Prof. Ehrenberg as somewhat doubtfully pertaining to this subtypieal form, 
we may regard as the earliest specimens those of the Lower and: Middle Lias of the 
north-east of France and of the Middle and Upper Lias of Somersetshire. lt appears 
E 
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