Papers on foraminifera Volume 1 - Softcover

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1893 Excerpt: ...by column E, with that of the warmer area typified by С and D, suggests some interesting facts in connection with the distribution of species. The larger arenaceous types pertaining to the family Astrorhizidœ, such as Astrorhiza, Saecammina, Storthosphœra, Rhabdammina, Jaculdla, Marsipella, and Hyperammina, are for the most part conspicuously absent from the colder portion of the channel, and appear to be partially replaced by the weaker forms of Lituolidœ. The genus Bulimina in its typical condition affects the warm area; whilst in the cold, the starved transition varieties which constitute the sub-genera Bolivina and Virgulina abound. The genus Lagena is represented in the cold region by a list of fifteen species; in the warm by only eight. The little thick-shelled Glohigerina borealis, so far as we know, is confined to the cold area, and, as has been stated, the gigantic Cornuspira striolata is similarly limited in distribution. How far these facts may indicate general laws can only be determiner by further investigation, and on the comparison of a larger series of soundings than are at present available. The following notes refer to species mentioned in the foregoing table, which are either new to science or otherwise present points of interest:--Planispirina contraría (Biloculina contraria, d'Orbigny).--Dr. Steinmann Neues Jahrb. für Min., 1881, voL L p. 37, pL 2), describes in detail the structure of the shell in this species, and shows sufficient grounds for separating it from the genus Biloculina. In point of fact, it is an intermediate sub-type, more nearly resembling Hauerina than Biloculina, but differing from the former in two important particulars, namely, the alar extension of the chamber-walls over the lateral s...