596 DR. A. MORLEY DATIES ON THE FAUNAS [vol. lxxix, 



of the internal ribs. It seems advisable, therefore, to distinguish 

 it by the trivial name suggested by A. d'Archiac & Ha hue, and 

 approved by Fedden in his 1879 list. 



Ostrea virleti Deshayes. (Text-iigs. 4-7, pp. 597, 598.) 



1836. Ostrea virleti Deshayes, in ' Expedition Scientifique de Moree ' 



vol. iii, p. 123 & pi. xxi, figs. 1-2. 

 1859. Ostrea virleti H. Abich, ' Das Steinsalz & seine Geologische Stellung 



im Russischen Armenien ' Mem. Acad. Imp. Sci. St. Petersb. 



ser. 6, vol. vii [ix], p. 124 & pi. iii, fig. 1, pi. v, figs. 1, 2. 

 1883. Ostrea virleti Th. Fuchs in Zittel, ' Beitriige zur Geologie & Paliion- 



tologie der Libyschen Wiiste ' Paheontographica, vol. xxx. Pal. 



Theil, pp. 43, 61, pis. iv & v. 

 1899. Ostrea (AlectryoniaJ virleti R. B. Newton, G-eol. Mag. p. 205. 

 1901. Ostrea iieguensis F. Nestling, ' Fauna of the Miocene Beds of Burma ' 



Pal. Ind. n. s. vol. i, pt. 3, p. 107 & pl.ii, figs. 1-2 6. 



Other comparable species : — 



1847. Ostrea crassicostata G. B. Sowerby, in J. Smith, Q. J. G. S. vol. iii, 

 p. 420 & pi. xix, fig. 23. (Miocene of Portugal.) 



1855. Ostrea vespertina Conrad, 'Pacific Railroad Report' [reprinted in 

 U.S. Geol. Surv. Prof. Paper 59, 1909, App. VI]. (Newer Mio- 

 cene of California.) 



1909. Ostrea djuvanaensis K. Martin, ' Die Fossilien von Java ' Samml. 

 Geol. Reichs-Mus. Leiden, n.s. vol. i, pt. 2, p. 334 & pi. xlvi, 

 figs. 1-4. (Older Miocene of Java.) 



This species is represented by six specimens from Minihagal- 

 kanda (Brit. Mus. L. 2S757-62), three consisting of both valves 

 inseparabty united in the natural position, and three of left valves 

 only. They show considerable variation in form and proportions, 

 and are all somewhat smaller than any of the figured specimens, 

 but agree with those and one another in having few, coarse, angular 

 ribs, occasionally bifurcating, and somewhat unevenly distributed 

 over the surface : ribs on one valve answering to svdci on the other. 

 Some of the specimens (particularly L. 28757, fig. 4) closely re- 

 semble Noetling's figures, others are more like the Egyptian speci- 

 mens. Most of them show, in greater or less degree, a tendency 

 to obliquely posterior elongation (as compared with the Greek and 

 Egyptian specimens), and in one case ( L. 28759, figs. 6 & 7) this 

 is combined with the development of what is practically a posterior 

 ear : the form then approaches that of O. crassicostata from the 

 Miocene of Portugal. 



The ligamental area is rather large and obtusely triangular : it 

 does not attain the great size shown in some of the Siwa specimens, 

 possibly because the Ceylon specimens are not full-grown or are 

 less gerontic. It is sometimes inclined towards the posterior end. 

 On the interior of the left valve there is a tendency to the 

 formation of two pits (fig. 5, p. 597), like those shown in 

 Fuchs's pi. iv, fig. 3, and less distinctly in other Siwa figures. 



The type-specimens of O. virleti should be in the Deshayes 

 Collection at the Ecole des Mines, Paris ; but I was unable to 

 find them in the course of a short visit. 



