REPORT OH THE FORAMINIFERA. 
253 
disposed to question the opinion of so experienced a microscopist as my friend Dr. 
Dawson ; but supposing the Rhizopod nature of the fossil established, the characters of 
the shell appear to suggest affinity with the calcareous rather than the strictly arenaceous 
types. 
In localities in which Sacccimmince abound, whether in the recent or fossil condition, 
it not unfrequently happens that almost the entire deposit is composed of their tests. 
Some of the soundings taken off Franz- Josef Land, during the Austro-Hungarian North 
Polar Expedition, showed that the sea-bed of that boreal region in many places consists 
of little else, and in the Carboniferous formation of the north of England and of 
Scotland, there are certain limestones which are almost exclusively made up of the 
remains of the polythalamous variety of the type. 
The distribution of the genus Saccammina is practically embraced in the geographical 
area inhabited by Saccammina sphcerica and the geological range of Saccammina carteri. 
The former affects moderately deep water, and is common only in the North Atlantic and 
Arctic Oceans. The earliest recorded appearance of the latter is in beds of Lower 
Silurian age at Girvan in Ayrshire (Nicholson and Etheridge), and it is plentiful in some 
of the Carboniferous limestones of both Great Britain and Ireland. A little uncertainty 
prevails about its occurrence in Mesozoic rocks, but the genus is stated by Rupert Jones 1 
to have been found in the Lias and possibly in the Lower Oolite. From a manuscript 
list, for which I am indebted to Dr. Rudolf Haeusler, I infer that it has been obtained 
from the Upper Jurassic beds of Switzerland, though it is not mentioned in his published 
catalogue. 
Saccammina sjohcerica, M. Sars (PI. XVIII. figs. 11-17). 
Saccammina sphoerica, M. Sars, 1868, Vidensk.-Selsk. Forkandl. for 1868, p. 248. 
„ „ G. 0. Sars, 1871, Ibid. for 1871, p. 250. 
„ ,, Carpenter, 1875, The Microscope, 5thEd., p. 532, fig. 272, ci.b.c. 
Test free or rarely attached ; globular or pyriform ; consisting typically of a single 
chamber with compact coarsely arenaceous walls, and a simple orifice situated in a nipple- 
like protuberance. Tests which are (or appear to be) polythalamous have the later 
segments small, imperfectly formed, and irregularly combined. Diameter from about Afh 
to -^th inch (1 to 3 '5 mm.). 
Saccammina sphcerica was discovered by the elder Sars, and the name first appears in 
a list of Foraminifera dredged by him at a depth of 450 fathoms on the coast of Norway. 
Neither specific description nor figures accompanied this catalogue, but specimens kindly 
furnished by Prof. G. 0. Sars to several subsequent observers leave no doubt as to the 
form for which the name was intended. 
1 Proc. Qeol. Assoc., 1872, vol. ii. p. 181, table. 
(ZOOL. CHALL. EXP. PART XXII. 1883.) 
Y 33 
