382 NOTES ON THE GEOLOGY 



ilar age. The hornblende slate, however, appears to be the oldest 

 vaiiety of that rock. The drusy quartz. No. 392, passing into 

 chalcedony, or even hyalite, is said to be abundant in the mica 

 slate of the island. The iron sand, No, 397, is cemented into a 

 rock, and the deposit increases daily on the seashore. It ap- 

 pears to be a mixture of fine clay and iron, and the latter probably 

 performs the part of a cement. 



The specimens sent me by Mr. Van Lennep from the island 

 of Rhodes, are very interesting. They consist of tertiary fossils. 

 Says Mr. Van Lennep, " I visited Rhodes lately, and found the 

 northern extremity of the island to contain an inestimable mine 

 of fossil shells : some in solid rock, others in a sandy deposit, 

 Avhich disintegrates by the action of the atmosphere." This sand 

 (No. 633) is made up of coarse gi*ains of different minerals, frag- 

 ments of shells, and many entire valves of shells. It has a green- 

 ish aspect, and considerably resembles gi'cen sand. The following 

 genera of fossils exist in the collection. The species are aU very 

 different from any with which I am acquainted, and the proba- 

 bility is that many of them are new : but I have not the means 

 of determining this point ; and therefore leave them unnamed, 

 with a few exceptions. 



No. 621. Clypeaster, Lam. Species not figured in Goldfuss's Petrefacta Germanise. 



No. 615. Pectunculus pulvinatus ? Lamk. Goldfuss's Petrefacta, Tab. XXXVI. fig. 5. 



No. 616. Turbinolia, approaching T. cuneata of Goldfuss ; Tab. XV. fig. 9, but 

 different. 



No. 617. Natica. 



No. 618. Pecteii, not figured by Goldfuss. 



No. 619. Dentalium. 



No. 620. Pyrula. 



No. 622. Turbo. 



No. 623. Lutraria : Length one inch and three fourths : breadth, three inches and 

 three fourths. 



No. 624. Cerithium. 



No. 625. « 



No. 626. Trochus. 



No. 628. Operculum of a univalve. 



No. 629. Fragments of Pecten, &:c. in chalky limestone. 



No. 631. Turritella with Serpula. 



No. 632. Serpula. 



No. 634. Pecluncuhis polyodonta, Bronn. This large species corresponds very closely 

 to the figure of P. polyodonta in Goldfuss's Petrefacta, Tab. CXXVI. fig. 6. It is said 

 by that author to abound ubiciinque, in stratis marinis svperioribiis Germajiia:. 



