24 



GEOLOGICAL MEMOIRS. 



Trochus eutrochus. 



Smyntheus. 



faustus. 



Oniistus Heberti, 

 Solarium Hornesi. 

 Pleurotomaria semiornata, Stol. 



Chryseis. 



Alaria tumida. 



ornatissima, Stol. 



Deslongchampsia loricata. 

 Patella asquiradiata. 

 Helcion rugosum. 



Balinense, Stol. 



Natica pertusa, Stol. 



Cornelia. 



Chemnitzia dilatata. 

 Mathilda euglypha. 

 Turbo Davidsoni. 

 Trochus Balinensis. 



2. Bivalves, by Dr. Lauhe. — Of the 108 species known to occiu' at 

 Balin, 59 have been found in Normandy, in the ^' Bathonien/' 

 " Bajocien," and even '^ Callovien " subdivisions; 71 are identical 

 with those of the Great and Inferior Oolite, and 40 with those of 

 the Middle Brown Jura of Swabia. Their coexistence within a 

 stratum of moderate thickness is another argument against the 

 general importance of the subdivisions of Jurassic deposits esta- 

 blished and maintained by French geologists. The 22 new species 

 from Balin are : — 



Eligmus contortus. Isoarca depressa. 



Placunopsis fibrosa. Cardiodonta Balinensis. 



oblonga. Corbis obovata. 



Plicatula lyra. Opis ceratoides. 



Lima strigillata. Astarte galiciana. 



Lycetti. Ceromya columba. 



complanata. Myacites Polonicus. 



globularis. Balinensis. 



Hinnites sublsevis. Saxicava crassula. 



Macrodon ornatum. Deslongchampsi. 



Isoarca ovata. Grastrochana pholadoides. 



3. Echinoderms, by Dr. Laube. — This Class is represented at Balin 

 by a small number of forms, generally agreeing with those of the 

 Prench and English Jurassic strata, and leading to the same con- 

 clusions as the Gasteropods and the Bivalves. The new species 

 are : — 



Pygaster decoratus. Magnosia Desori. 



Stomechinus cognatus. Hemicidaris Apollo. 



Pseudodiadema subpentagonum. 



4. Bryozoa, Anthozoa, and Spongiaria, by Prof. Eeuss. — Of the 19 

 species of Bryozoa, 12 of Anthozoa, and 5 of Spongiaria stated to 

 occur in the strata of Balin, 20 are already known from other 

 localities. Among them all the species of Bryozoa (with the excep- 

 tion of two, whose determination stiU remains uncertain) and 3 of 

 Spongiaria are identical with those from the ^' Bathonien" deposits 

 of Ranville, near Caen ; 6 species of Anthozoa (the 6 others being 

 new) are found either in the Great or in the Inferior Oolite of 

 England and Prance. The shells of Mollusca incrusted by these 

 Bryozoa belong partly to the " Bathonien," partly to the " Bajocien," 

 and even to the " Callovien " subdivisions, or to 4 species common to 

 the whole of these three subdivisions. It may be inferred from 

 these facts that these three subdivisions, more or less distinctly 

 limited in other localities, are united near Balin into one indivisible 

 stratum, whose characters coincide perfectly with those of the 



