378 Mr. Weaver's View ryEhrenberg's Observations 



Maksure, Barkan, Sanac and Ketumbul, and one an island 

 on the African side of the Red Sea, nam,el y, Massaua. 



It is possible that by repeated and closer examination of the 

 marine productions collected by us, many other Polythalamia 

 may be found besides those already discovered. In the mean 

 time, as a preliminary, I have drawn up a list of the species 

 hitherto met with*. From this it results that the total num- 

 ber of species of Polythalamia observed in the Red Sea are 

 Jifty, and in the Mediterranean, on the Libyan and Syrian 

 coasts, twenty-seven. The new species derived from the two 

 seas amount lo fifty -four ^ of which twenty-seven species are 

 peculiar to the Red Sea, and seventeen are common to both 

 seas. Particularly worthy of notice is the wide distribution 

 and massy development of the Peneroplis planatus and Sorites 

 Orbiculus, which are rare on the European coast. These forms 

 are not only present almost everywhere in the East, but con- 

 stitute the predominant masses. On the other hand, the Ro- 

 talia Becearii, which composes the Italian hills, occurs only 

 singly and very rarely in the Red Sea; and I nowhere found 

 it on the Libyan and Syrian coasts. The Sorites Orbiculus I 

 have also from St. Domingo. 



In reviewing these subjects, even a superficial comparison 

 of them with the contents of the chalk and chalk marl, is at- 

 tended with the striking result, that none of these living forms 

 are found among the animalcules of the chalk, not even anriong 

 those which compose the compact limestone of the Egyptian 

 and Arabian rocks, and which are still partly washed by the 

 sea near Hamam Faraun. 



Remarks on Polythalamia, 

 After a preliminary view of the researches of earlier la- 

 bourers in this branch of zoological inquiry. Dr. Ehrenberg ob- 

 serves:— A lively interest respecting the minute Polythalamian 

 bodies which enter into the composition of sea-sand was ex- 

 cited anew by the work of Alcide d'Orbigny in 1826, in which 

 are contained a great number of new species, while many of 

 those which were previously known are examined with greater 



* Of d'Orbigny 's nine species from the Red Sea, there are three which 

 I cannot identify, namely, Triloculina bicarinata, Quinqueloculina limbata^ 

 and Q,. punctata ; but the other six are probably these with which I have 

 become acquainted, and to which I have therefore given the same names, 

 namely, Textulana communis, Colcarina Defrancii, C. Gaudichaudii, Quin- 

 queloculina sulcata, and Vertebralina striata. His Jssilina {Nummidina) ni- 

 tida I hold to be the Sorites Orbiculus. 



Although I possess and have compared many of the Polythalamia which 

 have been described by d'Orbigny derived from the same localities, yet 1 

 am in want of a great number of the originals named by him, and as this 

 author has generally given new names unaccompanied by descriptions, 1 

 have not in most cases been able to determine to what form the name 

 given by him belongs. 



