IxXXvi PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



cation of the last part, which, whilst it completes the natural-history 

 portion of the work, contains also the Geological relations of the 

 strata examined and described. Without going into a minute detail 

 of the fossils described in this Second Part, it may be stated that in 

 the EcJmiodermata Messrs. Sandberger have added 1 species to the 

 Asteriadee, to the Echinidse 2 species of the still living genus Cidaris, 

 to the Crinoidea, of the characteristic features of whose organization 

 a very clear and detailed description is given, 2 genera, Myrtillo- 

 crinus and Stylocrinus, and 6 species, the second however in the genus 

 !Stylocrinus being founded on a species separated from the genus Pla- 

 tycrimis, the species here described being a Platycrinus of Goldfuss. 



1 have singled out this class as one perhaps of the highest interest, 

 and so large an addition of species in so limited a space affords 

 another example of the extraordinary increase in our knowledge of 

 the fauna of remote epochs, which every day is now affording us. 

 In the five sections into which the authors divide the Rhenish 

 Formations of Nassau, — namely (beginning from below), 1 . Spirifer- 

 sandstone, 2. Orthoceratite-schist, 3. Stringocephalus-limestone, 4. 

 Cypridina-slate, 5. Posidonomya-schist, — his tables contain, of Fishes, 



2 species, 1 belonging to each of the two more ancient sections ; 

 Crustacea 26, of which 2 are common to the two older sections, 2 to 

 the second and fourth, and 1 to the first, second, and fourth ; Annu- 

 losa 8, of which, one only belongs to the second, and the other seven 

 to the third section ; of Mollusca in the order Cephalophoda^ 151, of 

 which 1 species of Goniatite, Goniatites retrorsus, is common to sections 

 three and four : 1 species of Orthoceratites, Orthoceras triangular e, 

 is common to one and two ; Orthoceras planiseptatum, to one, two, 

 and four ; 2 species, Orthoceras lineare, O. arcuatellum, to three and 

 four; and 1, O. regulare to two and four. Of the Gasteropoda, 80, 

 of which no single species is represented as common to two divi- 

 sions of the shales, and about 80 per cent, of the whole belong to 

 the third section. Of the Pteropoda 12, of the Pelekypoda 

 73, of which 3 are common to the first and second sections, the 

 order preponderating as to number in the first section. Of the 

 Brachiopoda ^7, of which 3 species are common to the first and 

 third sections. Of Bryozoa 7, being all in the third section. Of 

 the Echinodermata 17, no species being common to two sections. 

 Of Polypi 1 8, of which 1 species is common to the first and second, 

 and 1 to the second and third. In Plants, 3 species belonging to 



3 different genera of vascular plants were found in the first section, 

 and 2 species also of different genera in the second section, not even 

 a single genus of the six enumerated being common to two sections. 

 Of vascular plants, the Acotyledones are represented by a single 

 species of 8 distinct genera, and the Dicotyledones by a single species 

 of 3 distinct genera, all occurring in the fifth section. I have 

 dwelt on this portion of the statistics of the works of Sandberger, 

 because, whilst it exhibits very strongly the individuality of each 

 of the five sections, it also affords some examples of the passage 

 of a species from a low zone to one higher in the series, though 

 apparently lost in the intervening zone. Examples of this kind 



