Notices of Memoirs — Radiolaria in Albite Crystals. 417 



found on the coast of Greenland. Mallotns villosus, Osmerus mordax, 

 Gasterosteus aculeatus, and Cyclopterus lurnpus, have already been 

 recorded from this deposit; and Sir William Dawson now adds 

 a species of Cottus, which seems to be C. fasciatus of Keinhardt. 

 Other nodules containing Nereid worms are also described, and 

 believed to represent a species of the genus Nereis. 



II. — The Occurrence of Radiolaria in Albite Crystals. 



A. Issel. Radiolaires FOS3ILES contenues dans les cristaux 

 d'albite. Compt. Eend. tome ex. pp. 420 — 424, Fevr. 24, 1890. 



A. Issel. Il Calcifiro fossilifero di Rovegno in Val di Trebbia. 

 Annali del Museo Civico di Storia Naturale di Genova, (2) ix. 

 1890, pp. 91—119, pis. v. and vi. 



PROBABLY one of the last places in which a geologist would 

 attempt to commence fossil collecting would be in a rock 

 containing authigenous crystals of albite, and perhaps the most 

 remarkable discovery announced in the present year is that not 

 onty does such a rock yield a Radiolarian fauna, but that the fossils 

 occur in the albite crystals themselves. The calciphyre, in which 

 this unexpected find has been made, occurs at several places round 

 Rovegno, a village situated in the tongue of Pavia that runs south 

 up the Trebbia valley to the summit of the Ligurian Apennines. 

 The rock occurs in a series of calcareous marls, calcareous and 

 argillaceous "schists" and tiles, belonging to the group of Upper 

 Eocene beds (piano liguriano), which has already yielded so many 

 interesting results. The beds are so much contorted that the 

 stratigraphical sequence is determinable but with difficulty ; the 

 fossiliferous rock, however, certainly belongs to the lower part of 

 the series, the upper part of which consists of serpentines, gabbro, 

 diabase, phtanite with pyrolusite, and breccias. The calciphyre 

 occurs intercalated with beds of hard, black, siliceous schist, which 

 together are 6-3 metres in thickness; the limestone is of a ground- 

 mass of ordinary cryptoerystalline calcite, in which are scattered 

 crystals of felspar; these are often minute in size, but range to 

 a length of 3 cm. Their crystallographic and optical properties 

 clearly prove them to be albite. Analyses of the rock and of the 

 insoluble residues are given; these, however, are less satisfactory; 

 thus in the former 10 per cent, of silica is accompanied by only 

 traces of alkalies; hence so much other siliceous matter must be 

 present that little can be learnt from bulk analyses. The Radiolaria 

 occur mostly within the albite, but sometimes a specimen projects 

 above the face of a crystal into the surrounding matrix. That the 

 structures really are Radiolaria there seems little room for doubt. 

 Prof. Issel has had considerable experience in the examination of 

 the Radiolarian fauna of the diaspores that occur in the same series; 1 

 while the plate of microphotographs that accompanies the second 



1 See, e.g. his recent paper, " Dei noduli a radiolarie di Cassagna e delle roccie 

 silicee e nianganesifere chi vi si connettono," Atti Soc. Ligus. Sci. Nat. e Geogr. 

 vol. i. No. 1, 1890. 



DECADE III. — VOL. VII. — NO. IX. 27 



