

424 Scientific Intelligence. 



the carbonate of lime previously noticed, when the solution of this 

 phosphate met with the silicates of potash or soda, whilst percolating 

 amid the rocks, the silicates would be decomposed by the carbonic 

 acid, and the phosphate of lime thrown down. We should expect, — in 

 the same manner as carbonate of lime often replaces the origimal mat- 

 ter of a shell which has been decomposed and removed from the body 

 of a rock, leaving those cavities commonly termed casts, — that phos- 

 phate of lime, in localities where from accidental circumstances it was 

 somewhat abundantly filtering through rocks, would also enter these 

 and other cavities, filling them under the needful conditions of deposit. 

 In like manner as we find carbonate of lime separating itself from mud 

 and silt in which it was disseminated, forming the nodules so common 

 in calcareo-argillaceous deposits, should we also expect disseminated 

 phosphate of lime to do the same under fitting conditions ; so that it 

 would not necessarily follow, however true in numerous cases, that 

 nodules containing much phosphate of lime were coprolitic. We can 

 readily imagine circumstances verv favorable for the solution and 



spread of these phosphates amid layers of mud and silt. We find such 

 phosphates surrounding some fossils, such as crustaceans from the Lon- 

 don clay, leading us to infer a connexion between the animal matter 

 and this substance. 



8. Arkose, (Bib. Univ., March, 1848.)— The arkose of the Vosges, 

 according to Delesse, is a metamorphic quartzite, consisting essentially 

 of hyaline quartz and crystals of orthose (feldspar.) 



III. Zoology. 



1. Conspectus Crustaceorum, <$-c, Conspectus of the Crustacea of the 

 Exploring Expedition ; by J. D. Dana,— continued. 



I CRUSTACEA ISOPODA. 



Appendices abdominales, duobus posticis exceptis, plerumque branchii- 

 formes, stylis caudalibus duobus aut nullis. Pedes thoracis 6 antici 

 ad eandem seriem pertinent, 8 postici ad seriem alteram,* excep- 

 tionibus raris (in lsopodis brachiatis.) 



L ISOPODA BRACHIATA. 



Pedes seriei posticse sex.t — Species Amphipodis affines (prsecipue 

 Dulichiis) ; habitum Caprelloidere ; ssepius algas, corallinas, etc. a 

 pedibus sex posticis affixes cum corpore arrecto. 



Familia 1. Arcturid^e. (Idotaeoideas.) 



_ • 



Pedes sex postici inter sese unguiculati similes. — Abdomen pauci- 

 articulatum, laminis operculiformibus infra opertum (sicut Idotais), 

 stylis caudalibus carens. 



quoque, styli camlales sex, et alii apj 

 optima et non negligenda. 



t Hac charaetere species illse aliis 



abdominales natatorii. Haec discrinnna 



