444- Mr. Weaver's /^7fW o/'Ehrenberg's Observations 



bar of sjiecies of Polythalamia observed in the Red Sea are 

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

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

 seas amonnt io Jtflij-four, of which hvcnti/seven species are 

 pecuhar 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 j^Ianatus and Sorites 

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

 are not only present almost ever3Hvhere in the East, but con- 

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

 talia Beccarii, wliich 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 Orbicidus I 

 have also from St. Uomingo. 



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 among 

 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 Poli/thalainia. 



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'Oibigny in 1826, in which 

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

 those which were previously known aie examined with greater 

 care, and an improved and easier view is taken of the whole 

 subject. By his active exertions he had collected between 600 

 and 700 species from the sea-sand of France, Italy, England, 

 the Isle of France, Sandwich Islands, the Malouine and Ma- 

 rian Isles, &c., of which, however, only 425 received names. 

 The whole mass of these microscopic animalcules, which he 

 a"-ain decidedly associates with the Mollusks and Cephalopods, 



and Q.. jnmctata ; but tlie other six are probably these with which I have 

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

 namely, Texlular'ia communis, Calcarina Defrancii, C. Gaiulkhaitdn, Qtiin- 

 (pieloc'idina sulcata, and VerlcbraUna striata. His /Issilina {Numwnliua) ni- 

 tida I hold to be the Sorites Orbicidus. 



Although I possess and have compared many of the Polythalamia which 

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

 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, I 

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

 given by him belongs. 



