ZOOLOGY. 329 



immense numbers ; sometimes their number seems almost to equal the 

 grains of sand. The bottom in this region is of a fine gray sand. We 

 may distinguish three regions characterized by foraminiferae ; the first 

 near the shore, without any, extends to about 15 fathoms ; the second 

 goes to about 60 fathoms, and is characterized by a great number of spe- 

 cies, of which the RotuUna Baihyii seems to be most numerously rep- 

 resented ; at about 60 fathoms the Globigerina preponderates, the Rotu- 

 lina disappearing, and this region extends to a depth not yet known. 



M. Pourtales has also pointed out, for the first time, a direct and 

 well sustained analogy which is to be found in the order of the suc- 

 cession of the cells of foraminiferce of several genera, and the succes- 

 sion of leaves in plants; so fully, that it can be expressed by the same 

 fractions with which botanists are in the habit of expressing phyllo- 

 taxis in the vegetable kingdom. This is, therefore, an important ad- 

 ditional link in the investigation of the plan which regulates the nor- 

 mal position of parts in organized beings, a link which may lead us to 

 include in one universal formula the rhythmic movements which preside 

 over the development of all finite beings, as the phyllotactic formulae 

 themselves are now known to express also the natural relations which 

 exist in the movements of the bodies belonging to our solar system. 

 Proceedings of the American Association. 



INFUSORIA OF THE DEAD SEA AND THE RIVER JORDAN. 



EHRENBERG has lately examined specimens of the water and sedi- 

 ment of the Dead Sea and the River Jordan in a zoological point of 

 view, and finds in the former an abundance of Infusoria, nearly all of 

 which are of fresh or brackish water species, indicating that this lake 

 never formed any part of the general ocean. The waters of the Jor- 

 dan also abound in Infusoria, all of the fresh-water kinds, a fact ren- 

 dering it probable that great rivers, like basins of the ocean, have 

 their peculiar and characteristic species. Jameson's Philosophical 

 Journal, Jan. 



AMERICAN FRESH-WATER MOLLTJSKS. 



AT a meeting of the Boston Society of Natural History, in Novem- 

 ber, Prof. Agassiz stated that he had been of late engaged in the study 

 of the soft parts of American fresh-water mollusks, and their relations 

 to the shell, with the object, if possible, of discovering some new 

 characters on which to base an accurate classification. He had found 

 that, in addition to the two muscular impressions in the shell usually 

 described, there are generally two or more impressions produced by 

 muscular fibres springing from the foot, which impressions in some 

 species are confluent, in others more or less distinct. Other distinctive 

 characters are observed in the arrangement of the mantle. In some 

 of the Naiades, the posterior portion of the gills only is found to be 

 distended with eggs at the breeding season, in others the whole gill is 

 so distended. In the former of these, Prof. Agassiz had found the 

 cavity containing the eggs to be limited at each end by transverse 



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