1870.] DAWSON — ON FOIIAMINIFEUA, 173 



iiently fresh, the roraininifcra become very scarce and poor. 

 Polystomeihi striatopimctata is the most couimon, but it has 

 become very small. Nonionina Labraclorica, Lituola Canarien.sis, 

 and Trochammina inflata also occur, but all much reduced iu size, 

 and scarce relatively to the amount of material examined. On 

 passinp; from the Gulf to the cast of Newfoundland, or to the 

 south of Cape Breton, a change from the Gulf Fauna is imme- 

 diately detected. Polystomella striatopuuctata, there so com- 

 mon, becomes rare. Nonionina Labradorica to a great extent 

 ceases to appear, and Uvigerina p3^gmaea and Cassidulinida; 

 become more frequent. 



The arenaceous liippocrepina, (Fig. 2,) and Lituola) (Figs. 1 

 and 3) are most plentiful at depths less than 20 fathoms. Lituola. 

 scorpiurus (Fig. 4) goes down to the greatest depths in Gaspe 

 Bay, and is yet abundant at 10 fathoms, while the immense 

 Rhabdopleura abyssorum (Fig. G) only appears at about 20 

 fathoms, and continues from that point increasing in numbers and 

 size to the depth of 50 fathoms, which is the greatest depth in 

 Gaspe Bay, where alone it has been found. 



The distribution of these Foraminifera would tend, with other 

 facts, to show that these organisms, together with most other 

 marine animals of low organization, do not depend, to any great 

 extent, on the depth or intensity of daylight, but almost entirely 

 on the temperature of the water, as Dr. Carpenter maintains in his 

 account of his recent deep-sea dredging, so that they would not 

 give very satisfactory evidence of the conditions of deposit ol' 

 Post pliocene or other beds, unless other facts were at disposal to 

 show the depth, when the Foraminifera would give valuable 

 assistance with regard to the climatic conditions at that depth. 

 The quality of bottom has however, much to do w^ith the 

 general fades of the Foraminifera, as with other animals. For, 

 as shown above, calm water, with a bottom composed of fine sand 

 and sediment, is particularly favorable to the arenaceous forms, 

 though, even under these conditions, they do not thrive in the 

 very cold, deep water (such as that below 100 fathoms) in the 

 open Gulf. A strong current at once causes all sandy Ibrms to 

 disappear, mostly, no doubt, from want of the fine materials 

 necessary for their shells, and brings in a large preponderance of 

 Truneatulinas, Lagenida3, &c. 



* The figures refer to tlio numbers oftlio W(iOLl-cat>. 



