1867.] SWA]??- PEIN-CESS ISLA2fDS, SEA OF MARMORA. 381 



Fossils in the Museiun of Practical Geology it is called L. hyhrida. 

 Mr. Davidson, in his Ponograph of the Devonian Brachiopoda, 

 refers it to the Carboniferous species L. squamiformis, and remarks 

 that '^ it is difficult to obtain specimens preserving their natural 

 shape, almost every example being deformed or put out of shape 

 from the effects of pressure or cleavage." LinguJa squamiformis is 

 described as "longitudinally oblong, one- third or less longer than 

 wide ; valves slightly convex, with their external sui'face covered 

 with numerous fine concentric striae or lines of growth. Usual 

 dimensions 9 lines in length by 5 in width." Taking this as the 

 specific character of the shell, we find at Sloly that, besides lAngula 

 squamiformis, there is also another LinguJa, which must be either a 

 new species or, at least, a well-defined variety. A comparison of a 

 great number of specimens shows that the breadth of this shell is 

 equal to its length, or nearly so. Dimensions 5 Knes in length by 

 5 in width ; valves convex, and generally marked with two lines of 

 growth. jSTumerous fine intermediate striae cover the surface of the 

 valves, and give them a peculiar laminated appearance. Should 

 this LinguJa prove to be a new species, the name L. circuJaris might 

 be appropriate, since it difiPers so materially from the other LhiguJce in 

 having a form which is nearly orbicular. I should perhaps add that 

 the difference in shape from L. sqiuxmiformis could scarcely be due 

 to distortion, effected by either cleavage or pressure ; and I have 

 observed that when several individuals of these two species occur on 

 the same slab of slate, they in every case have retained their inde- 

 pendent and characteristic form. 



9. On the Geology of the Peixcess Islands in the Sea of Mae- 

 MOEA, By W. E. SwAN^, Esq. 



(Communicated by Sir R. I. Murchison, Bart., X.C.B., F.E.S., F.G.S., &c.) 



[The publication of this paper is unavoidably deferred.) 



(Abstract.) 



Me. Swax points out the existence of a considerable mass of Devo- 

 nian strata, partly fossihferous, in several of these islands, of an age 

 different from that of the beds of the Bosphorus, which latter he has 

 shown in a former paper to belong to the lowest of the Devonian 

 series of the Rhine. The presence of the remains of fish in the 

 above strata, and of an ancient coral-reef in one of these islands 

 (Andirovitho), is also noticed. 



The rocks which form the remaining portions of these islands are 

 (1) Trachytic, of younger age than the Devonian strata, and (2) 

 Trappean, more recent than the Trachytic. The quartz-rocks, of 

 which some of the islands are largely, and others entirely composed, 

 are altered sandstones of Devonian age. 



2ii2 



