250 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



by the intense heat of the sun, and are on this account exceedingly- 

 difficult for a horseman to traverse. They afford a rich soil for the 

 cultivation of maize, rice, water-melons, cucumbers, and the ordinary 

 vegetables of the x\rabs; and they frequently contain imbedded 

 shells of extinct species of the genera Cyrena, Unio, Melanopsis^ 

 Helix, &c. At the junction of the Diyala River with the Tigris 

 below Baghdad the deposit is a tenacious deep-red clay, derived from 

 the Hamrine red range, through which this river passes in its course 

 from the higher mountains. 



At Baghdad the foundations of all good buildings are laid on this 

 clay, at a depth of 1 5 or 18 feet below the surface, upon which rests 

 an arenaceous grey clay used for common fictile purposes. During 

 an extraordinary rise of the Tigris in the spring of 1849, the deposit 

 on its banks at Baghdad attained the height of six feet. 



(B.) The marine beds of the alluvium are much more extensive 

 than the fluviatile, and consist of dark-grey or reddish-yellow loose 

 sands and sandy marls. These are usually seen in the desert, at 

 some distance from the rivers ; and, where not otherwise distin- 

 guishable from the beds of the underlying rocks, are to be recognized 

 by the growth of saline plants, and by dark wet patches, produced 

 by the presence of chloride of sodium. They are sometimes accom- 

 panied by fossils. 



In the neighbourhood of Mohammerah, Sablah on the Karun, and 

 Busrah, are the following shells, identical with species now living at 

 the mouth of the Persian Gulf, — so far at least as they have been 

 compared with a small collection, made by the late Captain New- 

 bold, E.I.C.S., from the beach of Bushir. (Identified specimens are 

 marked with an asterisk.) 



Fossil Shells from Mohammerah, Sdhlah, and Busrah. 



Venus. Neritina crepidularia, *Purpura (Rapana). 



Area. Lamk. *Cerithium. 



Melanopsis. Purpura. Cyprsea. 



Strewed over the desert in the neighbourhood of the extensive 

 ruins of Worka and Sinkara, in Lower Chaldaea, and on the verge 

 of the marshes of the Euphrates, are innumerable fossils, of which I 

 collected 30 species, many of the specimens exhibiting distinct traces 

 of colour. The Arab women of the Madan tribes collect and wear 

 them in their hair as ornaments. 





Fossils from 



Worka and Sinkara 



. 



Astraea. 





Neritina sp. 



Strombus. 



Meandrina. 





Nerita. 



Nassa. 



Balanus ? 





Trochus. 



Colurabella. 



Venus. 





Cerithium. 



Mitra. 



*Cardium. 





Planaxis sulcata. 



Cyprasa ; 2 sp. 



Spondylus. 





Purpura. 



Aneillaria. 



Dentalium 



octangulura. 



* (Rapana). 



Oliva. 



sp. 





Murex. 



Conus ; 2 sp. 



Melanopsis 





Triton ? 



Otolite of a Fish 



Neritina crepidularia, Lamk. 







Mr. Ainsworth met with abundance of similar fossils near the first- 



