176 P. T. CLEVE ON SOME FOSSIL MARINE DIATOMS. 



ffemiauliiSj and is nearly related to Stephanofiyxis limbata, Ehr. 

 (Van Heurck Syn., PI. 83, ter. f. 13-14.) PI. 13, f. 18. 



Some 80 species of Diatoms have been found in the Tegel of 

 Briinn, and with the two exceptions Campylodiscus hibernicus and 

 C. Clypeus (the former occurring in fresh and the latter in brackish 

 water) ; all are decidedly marine. Only a comparatively few 

 appear to be extinct, and of those a remarkable number have been 

 detected in the " Moron deposit," which is said to be found near 

 Seville, in Spain. 



Of the recent species many forms are now living in the far-dis- 

 tant seas of Japan, California, West Indies, &c, proving that 

 the Tegel was a deposit in a sea of a tropical or sub-tropical 

 character. 



It is of great interest to compare these fossil forms with recent 

 specimens, and to note how little their characteristics have been 

 altered by the conditions to which they have been exposed during 

 the long period that has elapsed since the later tertiary and the 

 present time. 



Specimens of the Tegel Diatoms, mounted as " Typen Platten " 

 can be obtained of Herr Thum, 2, Teichstrasse, Leipzig. 



Additional Forms Found by F. Kitton in a Sample of the 

 Tegel, Cleaned by Herb, Thum. 



Campylodiscus Echeneis, not unfrequent. 



Nitzschia circumsuta, several valves. 



Surirella elegans? several valves, only differs from the fresh- 

 water form in the canaliculi being more robust. 



Stauroneis jihamicenteron, fragment of a valve. 



Nitzschia scalaris, fragment of a valve. 



Navicula major, two valves. 



Trinacria excavata, one valve. 



Aidacodiscus angidatus, one valve agreeing exactly with a speci- 

 men in my collection, identified by Dr. Greville. 



Aidacodiscus, n.sp. When the lower surface is in focus it is some- 

 what like a coarse A . margaritaceus, but when the objective is focussed 

 on the upper surface the markings very much resemble those in Aida- 

 codiscus (Eupodiscus) Argus. The furrows are much more dis- 

 tinct than those on A. margaritaceus ; number of processes, 6 ; 

 diameter of valve '0040. 



A. Grunowii docs not appear to be very rare in the Tegel, as 



