EEPOET ON THE FOEAMINIFEEA. 
559 
The test of Polymorpliina is almost invariably free ; there is, however, little 
doubt that one species with somewhat exceptional characters, Polymorpliina concava, 
Williamson, is parasitic when living ; and the “ cervicorn ” varieties are not unfrequently 
found growing attached to foreign bodies. 
The dimorphous modifications of Polymorpliina , those in which the early spiral 
segments are succeeded by a straight or curved linear series, constitute the subgenus 
Dimorphina of d’Orbigny. Such forms are rare. As a group they correspond morpho- 
logically to Sagrina and Clavulina, the dimorphous representatives of Uvigerina and 
Valvulina respectively. 
The geographical distribution of Polymorpliina, within certain bathymetrical limits, is 
world-wide. It is found in the Arctic Seas, as far north as lat. 79° 35' N., and in the 
opposite hemisphere nearly as far south as Kerguelen Island, lat. 46° 46' S. It is 
essentially a shallow-water genus, and is most abundant at depths of less than 80 or 100 
fathoms. At the same time there are certain forms of which fine examples are met with 
as low as 400 fathoms, and some of the smaller starved varieties are present even to 
depths of 2000 or 2500 fathoms. 
The geological range of the genus extends back as far as the Upper Trias of Derby- 
shire (Jones and Parker), and the Raibl Beds of South Germany (Giimbel) ; it becomes 
tolerably common in the Lias, and thenceforward is found in microzoic rocks of every 
successive period. 
Polymorpliina lactea, Walker and Jacob, sp. (PI. LXXI., typical, fig. 11 ; var., 
fig. 14). 
“ Serpula tenuis ovalis lsevis,” Walker and Boys, 1784, Test. Min., p. 2, pi. i. fig. 5. 
“Polymorpha Subcorcliformia vel Oviformia ,” Soldani, 1791, Testaceograpliia, vol. i. pt. 2 
p. 114, pi. cxii. figs. U, nn, &c. 
Serpula lactea, Walker and Jacob, 1798 ( fide Kanmacher), Adams’s Essays, 2nd ed., p. 634, 
pi. xxiv. fig. 4. 
Vermiculum lactewm, Montagu, 1803, Test. Brit., p. 522. 
Polymorpliina lactea , Macgillivray, 1843, Moll. Aberd., p. 320. 
Aretliusa lactea, Thorpe, 1844, Brit. Mar. Conch., p. 233. 
Globulina lachryma, Eeuss, 1845, Yerstein. bohm. Kreid., pt. i., pp. 40, 110, pi. xiii. 
fig. 83. 
Pyrulina ovulum, Ehrenberg, 1854, Mikrogeologie, pi. xxxi. figs. 35, 36. 
Polymorpliina muensteri, Eeuss, 1855, Sitzungsb. d. k. Ak. Wiss. Wien, vol. xviii. p. 249, pi. 
viii. fig. 80. 
Globulina roemeri, Id. Ibid. p. 245, pi. vi. fig. 63. 
Polymorpliina lactea, typica (pars), Williamson, 1858, Eec. For. Gt. Br., p. 71, pi. vi. fig. 147. 
,, lactea, var. communis, Id. Ibid. p. 72, pi. vi. figs. 153-155. 
„ lactea, Brady, Parker, and Jones, 1870 (Monograph of Polymorpliina), Trans. Linn. 
Soc. Bond., vol. xxvii. p. 213, pi. xxxix. fig. 1, a-c. 
