430 MK. E. B. NEWTON ON THE 



8. ? POEITES LEIOPHTLLA, vov, Beuss*, 1847. 



The collection includes a large nodular corallum 100 mm. long 

 by 80 mm. wide and 40 mm. thick, which is a cast of a Porites. 

 It agrees in characters with Abich's | description of the coral 

 from the islands of Lake Urmi referred to P. leiophylla. It 

 differs from von Eeuss' type of that species by the greater 

 size of the corallites. This feature may only be the result of the 

 greater size of the corallum. The coral is only a cast, so that 

 its determination is difficult", and it may be provisionally left in 

 the species to which Abich assigned it. The corallites in the 

 present specimen vary from 7-10 mm. in diameter. 



EXPLANATION OF PLATE 28. 



Fig. L Clypeaster imperialis, Mich., side view, nat. size. 



2. Clypeaster Guentheri, n. sp., side view, nat. size, 



3. Transverse and radial sections of Thamnarcea ]polymo7'pha, x 10 diam. 



Tortonian, Koyun Daghi, Lake Urmi. 



a. Transverse section across a series of corallites, X 10 diam. 



b. Section across part of a transverse section of a branch, showing 



the corallites cut longitudinally, with the synapticular plat- 

 forms. 



MAEINE TEETIART [MIOCENE] MOLLUSCA. 



By K. BuLLEN Newton, E.G-.S., of the British Museum 

 (Natural History). 



(Plates 29 & 30.) 



iNTEODrCTION. 



This communication deals with a number of Marine Tertiary 

 Mollusca obtained from Lake Urmi and its vicinity by Mr. E. T. 

 Giinther, who has generously presented the specimens to the 

 Geological Department of the British Museum. 



The specimens are mostly casts and frequently much water- 

 worn, yet of considerable interest since they serve to increase the 

 number of species already recorded from this area. 



* Von Eeuss, "Foss. Polyp. Wien. Tertiarb.," Haid, Naturw. Abh. vol. ii. 

 pt. 1, p. 28, pi. V. fig. 4. 



t Abich, 1859, op. cit. p. 101. 



