rOSSIL COEALS OP LAKE UiJMI. 429 



gr.mulations have been thus obliterated. In the compactness of 

 the exotheea the corals approach Abich's Astrea grandistella *, 

 which, owing to the absence of columella, is probably also a 

 Pliyllocoenia ; but as the nature of the exotheea and union of the 

 corallites is not shown by the figures, its generic position cannot 

 be absolutely determined. 



The two specimens from Koyun Daghi are flat-topped, tabular 

 coralla, and in the larger specimen the corallites show a tendency 

 to become elliptical or subtriaugular. 



There is a third sj^ecimen in Mr. Gruuther's collection from 

 Koyun Daghi referable to Fliyllocoenia ; it h.as well raised cali- 

 cular margins, as in P. irradians, Ed. & H. t, but the fragment 

 is too small and worn for satisfactory determination. 



7. Thamnae-sia poltmoepha {Abich) J, 1859. (Plate 28. 



fig. 3.) 



This interesting coral was well figured by Abich, whose speci- 

 mens came from Lake Urmi and Malischent or Maku. Their 

 specific identity with specimens collected on Koyun Daghi by 

 Mr. Giiutber is unquestionable. The horizon of the coral 

 on this island is settled by the fact that one of them is at- 

 tached to an Ostrea which Mr. E.. B. jSTewton has identified as 

 O. Virletl. 



The generic position of the coral is a matter of some interest, 

 as Thamnarcsa has not previously beeu recorded from Miocene 

 or even Cainozoic deposits. That the coral is not a Pontes is 

 shown by three characters : the absence of pali, the strongly 

 developed, imperforate septa, and the presence of the conspicuous 

 synapticular platforms, which are well shown in Abich's figures. 

 On casual inspection the coral appears spongiform rather than 

 corallian in structure. 



Thamnarcsa was founded by Thurmann & Etallon § in 1864, 

 and has recently been discussed by Dr. Ogilvie |[, who includes 

 it in the Madreporidse ; but, with. Etallon, vou Zittel, and 

 Duncan, I include it among the Microsolenidae. 



* Abich, 1859, op. cit. p. 92, pi. ii. fig. 3. 



t This species has been recorded from the Oligocene of Eriyan by Abicli, 

 1882, op. cit. p. 257, pi. vii. fig. 16. 



\ Porites folymorpha, Abich, 1859, op, cit. p. 100, pi. ix. figs. 1, a-e. 

 § " Leth, Brunt.," Neue Denk. schweiz. Ges. Naturw. vol. xx. p. 411. 

 II M. M. Ogilvie, " Kor. Strarab. Sch.," Palieontogr. Suppl. ii. pt. 7, p. 153. 



