Species of Paleozoic Bivalved Entomostraca. 405 



rites, Serpulites, Encrinites, Bellerophon, Productus, Terebratula, 

 Cardium, Nerita, Trochus, TurriteUa, &c." 



The so-called Cytherce (some are found to be of different ge- 

 nera) are thus described (p. 65) : — 



"15. Cy there Okeni, nob. With a smooth, somewhat flat, nearly 

 egg-shaped, large shell. 



"16. suborbiculata, nob. With a smooth, nearly orbicular, 



somewhat flat shell. 



"17. inflata, nob. With a smooth, very gibbous, nearly egg- 

 shaped shell. 



" 18. Hisingeri, nob. With a somewhat kidney-shaped smooth 



shell, like a small Modiola. 



" 19. elongata, nob. With a much longer shell, incurved at 



the middle on both sides, and smooth. 



"20. bilobata, nob. With a broad, strongly kidney-shaped, 



incurved shell, which often has both valves. 



"21. subcylindrica, nob. With a smooth, nearly cylindrical 



shell. 



" 22. intermedia, nob. With a smooth, bent, somewhat kidney- 

 shaped shell, which seems to be a passage-form between 

 C. Hisingeri and C. elongata." 



Count Minister intended that these should have been figured 

 in Goldfuss's great work on the Fossils of Germany; but they 

 have remained until now without illustration. The originals are 

 still in the Royal Museum at Munich ; but, through the kind 

 intervention of our friend Dr. A. Oppel, the Keeper of that 

 Museum, Herr Giimbel, State-Geologist of Bavaria, has most 

 courteously lent us a series of specimens corresponding to those 

 in the Munster Collection, and which he has obtained from the 

 same Carboniferous Limestone, at Tragenau, near Hof. Some 

 of the specimens are in good condition ; others, on the contrary, 

 are much worn, either by rolling, or probably by having been 

 partly dissolved by percolating water. 



By the careful comparison of these specimens with species 

 published since the date of Count Miin ster's paper, we are en- 

 abled to remove some difficulties that lie in the way of settling 

 the nomenclature of the Upper Palaeozoic Bivalve Entomostraca, 

 among which there is much confusion — the more so since some 

 of the Carboniferous species continue to appear in the Permian 

 rocks, and have been described and named anew without refer- 

 ence to their earlier occurrence and naming; and, again, one of 

 us, in describing some Permian forms, adopted for one* of them 

 one of Count Miinster's names, urged by too great care in the 

 avoidance of new terms, and by some rashness in trying to re- 



* Cythere elongata, Jones ; subsequently modified, on good grounds, by 

 Geinitz to ft subelonyata. 



