558 Reviews — Recent Papers on Palceozoic Ostracoda. 



1500 feet below the existing level. How to reconcile all tlie facts 

 and explanations is left a good deal to the imagination of the reader. 



The formation of the Lower Boulder-clay is held to be due to ice, 

 " either in the form of a glacier, or of a sheet spread over the 

 country, and moving in certain directions." The Upper Boulder- 

 clay, which by-the-bye " may easily be mistaken for the Lower 

 Boulder-clay," sometimes shows traces of stratification, and is "just 

 such a deposit as might be supposed to have been formed under 

 the sea, the waters of which were laden with ice-rafts and bergs 

 bearing stones and boulders which would constantly fall to the 

 bottom as the ice melted away ; while these waters were themselves 

 rendered turgid by streams from glaciers entering from various 

 directions." 



The first part of the work is thus taken up with an account of 

 the many geological formations that occur in Ireland ; the second 

 part deals with physical geography, with the ' birthday ' of 

 mountains, the origin of the Central Plain, and of river valleys and 

 lakes ; and the third part is devoted to the Glaciation of the country, 

 concluding with some account of the Prehistoric Mammalia. 



The work is pleasantly written and well calculated to arouse an 

 interest in Irish geology ; and from its containing the matured views 

 of one who for many years directed tlie Geological Survey of the 

 country, it will be read with interest by geologists in general. 



IV. — Some Eeoent Memoirs on Paleozoic Ostracoda. 



-r TTLEICH, E. 0., describing some new or little-known North- 



\j American Palaiozoic Ostracoda (Journ. Cincinnati Soc. 

 Nat. Hist., 1890 and 1891) adds very considerably to our knowledge 

 of the — 1. " Lower Silurian ;" 2. " Upper Silurian and Devonian ;" 

 and 3. " Carboniferous " species. In the first group he finds reason 

 to separate some known forms from Beyrichia as types of the new 

 genera Ctenobolhina (with 5 species) and Tretradella (1 species) ; 

 and to institute the new genera DrepaneUa (6 species) and Jonesella 

 (4 species), both near Bollia. The other genera of this group, from 

 Ohio, Kentucky, Tennessee, Indiana, Illinois, and Minnesota, here 

 described and figured, are Entomis, 1 sp. ; Pontocypris (?), 1 sp. ; 

 Bollia, 5 spp. ; Placentula, 2 ; Beyrichia, 1 ; Eurychilina, 6 ; Primitia, 

 11 ; Aparchites, 1 ; Leperditia, 5 (including a clear determination 

 of L. fabulites, Conrad) : and Isochilina, 6 (one from Ontario). The 

 second group come from Indiana, Ohio, and New- York State, and 

 consist of Leperditia, Isochilina, Aparchites, and Entomis, 1 sp. each; 

 ^chmina, 2 spp, : Halliella, gen. nov., 1 ; Ctenobolhina, 5 ; Bollia, 

 2 ; Beyrichia, 3 ; Moorea, 1 ; Kirkbya, 3 ; Octonaria, 4 ; Bythocypris, 

 3 ; Bairdia and Pachydomella, gen. nov., 1 sp. each ; and Barychilina, 

 gen. nov. 2. The third (Carboniferous) group comprises — Leper- 

 ditia, 1 sp. ; Primitia. 4 spp. ; Ulrichia, 2 ; Beyrichia, 2 ; Bollia and 

 Moorea, 1 each ; Kirkbya, 5 ; Cypridina, Cytherella, Bairdia, and 

 Pontocypris (?), 1 sp. each. The species are illustrated in eighteen 



