REPORT ON THE FORAMINIFERA. 
199 
The essential characters of the test in Cornuspira can be stated in very few words. 
It is discoidal or complanate in contour, and consists simply of a non-septate porcellanous 
tube coiled upon itself in one plane, the open or very slightly constricted end serving as 
the aperture. It is isomorphous with Spirillina in the hyaline, and with Ammodiscus 
in the arenaceous series. 
The Cornuspirce are connected with the true Miliolce by Kiibler’s genus Oplithalmidium, 
which embraces a number of dimorphous varieties, spiral and non-septate in their earlier 
stages, and subsequently Spiroloculine in their mode of growth. The affinity of the 
genus with Planispirinct and Hauerina is indicated by the little discoidal Planispirina 
exigua, the shell of which is planospiral throughout, but the early whorls are non-septate like 
Cornuspira, whilst the later convolutions are segmented as in the two former genera. 
Lastly, its relationship to Orbitolites is attested by the deep-sea Orbitolites tenuissima, in 
which not only is the initial portion of the test distinctly Cornu spiriform, but 
occasionally even the later whorls revert to the non-septate condition. 
One or two species of Cornuspira attain large dimensions, but for the most part the 
genus is represented by specimens of relatively minute size. 
The geographical range of the genus is world-wide, without much reference to latitude 
or depth of water. The finest known specimens, however, are from various points in the 
North Atlantic, at depths of from 300 to 600 fathoms. 
Its geological distribution probably commences with the Liassic period, but some 
doubt exists as to the Mesozoic species, owing to the failure of authors to discriminate 
between Cornuspira and the isomorphous genera. From the commencement of the 
Tertiary epoch it is found in microzoic deposits of almost every age down to the present 
time. 
Cornuspira foliacea, Philippi, sp. (PI. XI. figs. 5-9). 
Orbis foliaceus, Philippi, 1844, Enum. Moll. Sicil., vol. ii. p. 147, pi. xxiv. iig. 26. 
Operculina striata, Czjzek, 1848, Haidinger’s Nat. Abhandl., vol. ii. p. 146, pi. xiii. figs. 10, 11. 
„ plicata, Id. Ibid., p. 146, pi. xiii. figs. 12, 13. 
Cornuspira planorbis, Schultze, 1854, Organism. Poly thal., p. 40, pi. ii. fig. 21; — 1860, 
Wiegmann’s Archiv, p. 287. 
Operculina ammonitiformis, Costa, 1856, Atti dell’ Accad. Pont., vol. vii. p. 209, pi. xvii. 
fig. 16. 
Spirillina foliacea, Williamson, 1858, Rec. For. Gt. Br., p. 91, pi. vii. figs. 199-201. 
Cornuspira foliacea, Parker and Jones, 1865, Phil. Trans., vol. civ. p. 408, pi. xv. fig. 33. 
Cornuspira foliacea may be taken as the type of the genus. The test is pro- 
portionately thinner and flatter than that of most of its congeners, and the successive 
convolutions widen more rapidly ; it is devoid of exogenous ornament, but often marked 
with curved transverse lines of growth. The aperture, in fully grown specimens, is a 
