MIOCENE MOLLUSCA OF LAKE UEMI. 445 



The true P. Malvince possesses a greater number of ribs, which 

 radiate in straight lines from the umbone without any apparent 

 curvature on the lateral areas. The present Persian specimens 

 ar« probably more closely allied to P. opercularis of Linnfeus, 

 from which they are most difficult to separate after comparison 

 with the Pliocene representatives of this species contained in the 

 " Searles Wood " collection in the British Museum. This par- 

 ticular form of Pecten belongs to P. Fischer's sub-genus ^qui- 

 pecten, founded in 1886 on P. opercularis, Linnaeus, sp. 



Locality. Beach specimens from the island of Koyun Daghi ; 

 Dr. Abich's specimens were obtained from the " Urmia Plateau." 



'Formation. Miocene (Helvetian). 



Chlamts sp. indet. 



Two specimens have been determined as above. One consists 

 of an impression of a valve in a small block of limestone. It 

 possesses numerous radial, almost contiguous costse, which are 

 divided up into twos and threes such as are typical of P. gloria- 

 maris of Dubois from the Polish Miocene, but without the 

 echinations on the ribs distinguishing the European form. It is 

 of ovately oblong shape, and from the character of the costse 

 clearly belongs to the genus Ghlamys. The other specimen has 

 similar costal details, and was obtained from the island of 

 Koyun Daghi. 



Locality. In a cream-coloured limestone with foraminifera and 

 other small organisms, found on the road from Sujbulak to the 

 Plain of Solduz; and from the cliff of the island of Koyun 

 Daghi. 



Formation. Miocene (Helvetian). 



Chlamts sp. indet. (Plate 29. fig. 3.) 



This specimen has about 16 rounded costse divided by deep 

 and wide grooves which are feebly marked by extremely fine 

 oblique striations ; the costse show obscure indications of dividing 

 besides being ornamented with numerous slightly elevated scabrse 

 or spines. There is only one example of this form in the collec- 

 tion ; it has both valves attached and is considerably worn so 

 that the sculpture is difficult to define ; its dimensions in milli- 

 metres =height 42, length 38, and depth 18. The specimen is 

 probably related either to P. gloria-mar is, Dubois, P. opercu- 

 laris, Linnseus, sp., or to P. pusio, Linnseus, all of which are 



