374 Scientific Intelligence — Geology. 



Tried the relative density of the water of this sea and of the At- 

 lantic, — the latter from 25° N. latitude, and 52° \V. longitude ; dis- 

 tdled water being as 1. The water of the Atlantic was 1-02, and 

 of this sea 113. The last dissolved y^-, the water of the Atlantic \, 

 and the distilled water j\ of its weight of salt. The salt used was 

 a little damp. On leaving the Jordan, we carefully noted the 

 draught of the boats. With the same loads, they drew 1 inch less 

 water when afloat on this sea than in the river.* — {Expedition to the 

 Dead Sea and the Jordan. By W. F. Lynch?) 



6. Currents in the Gut of Gibraltar. — Some curious investigations 

 have been i'or some time carried on in the Gut of Gibraltar, by M. 

 Coupvent des Bois. He has proved, as a certainty, the existence of 

 a superficial current flowing from the ocean into the Mediterranean, 

 and of a deep under current flowing from tbe Mediterranean into the 

 ocean. He has also ascertained that between these two currents 

 there exists a bed of water which is in perfect repose. — (^Athenceum, 

 No. 1138, p. 842.) 



GEOLOGY. 



7. Barrande on the Trilobites of Bohemia. — Sir Roderick Mur- 

 chison has recently received a letter from M. Barrande of Prague, 

 who is preparing a work on the Silurian System of Bohemia, 

 and who in studying the numerous trilobites which he has col- 

 lected in that country, has made a remarkable discovery in respect 

 to these the most ancient fossil crustaceans in the crust of the 

 globe. M. Barrande has traced for the first time the develop- 

 ment of a trilobite (liis Sao Idrsuta) from its embryonary state 

 to its adult condition ; and has observed twenty successive stages, 

 during which this one species undergoes very remarkable changes 

 of organization, passing from a simple disc-like body to a fully 

 formed trilobite with seventeen free thoracic segments and two 

 caudal joints. This discovery is not only most interesting to pliy- 

 siologists, but highly important to geologists, as diminishing the num- 

 ber of the so-called species ; it being ascertained that in a work re- 

 cently published by MM. Hawle and Corda upon the trilobites of Bo- 

 hemia, the authors made no less than ten genera and eighteen species 

 out of a part only by the stages of metamorphosis of the Sao hir- 

 suta (Ba.i-r.)— (Athenaeum, No. 1132, p. 696, 7th July 1849.) 



8. The Fossil Foot-marks of the United States, and the Ani- 

 mals that made them. By Ediuard Hitchcock, D.D., LL.D., 

 President of Amherst College, and Professor of Natural Theology 

 and Geology. {From the Transactions of the American Academy 



* Since our return, some of the water of the Dead Sea has been subjected to 

 a powerful microscope, and no animalculae or vestige of animal matter could 

 be detected. 



