Miscellaneous, 407 



BIBLIOGRAPHICAL NOTICE. 



On supposed Remains of Organisms from the Pre-Camhrian Strata of 

 Brittany. By Hermann Eauff, of Bonn, With illustrative 

 cuts. 



Ueber anf/ehlic/ie Organismcnreste u. s. w. rrom the ' Neues Jahr- 

 buch liir Miueralogie,' &c., 189G, Bd. i. 



The Author reviews the results arrived at by M. Cayeux in his 

 microscopic researches in these old rocks. After examining speci- 

 mens himself, Herr Rauff thinks that the so-called Sponge-spicules 

 are inorganic — merely microscopic threads and granules of some 

 decomposed metallic mineral, most likely pyrites. 



He notices the extremely minute size and relatively enormous 

 number of the so-called Radiolarians. He observes that M. Cayeux 

 regards the matrix as having been crystallized from an original 

 state of Radiolarian earth ; and Rauff asks if any one could deter- 

 mine optically the isotropic nature of the delicate and thin shells 

 and skeletons in the anisotropic enveloping material. He also asks 

 why M. Cayeux holds it possible that the Radiolarian skeletons, in 

 spite of the crystallizing of the quartzose medium in which they lie, 

 could keep their original colloidal silica, whilst for his Sponge- 

 spicules he does not allow of its possible preservation. Rauff con- 

 cludes that these so-called Radiolarians and Sponge-spicules are 

 minute spherical granules of some modified metallic mineral, probably 

 pyrites, in touch or coalescence one with another. Independent 

 corroboration of his views he finds in Dr. Hiude's remarks on some 

 similar minute bodies in the ' Quarterly Journal of the Geological 

 Society,' vol. li. p. 631. 



MISCELLANEOUS. 



Modifications jyroduced in the Organs of Sense and of Nutrition in 

 certain Arthropods by confinement in Caves*. By M. Akmand Vire. 



NoAVHERE does the influence of environment show itself more 

 markedly or in a more striking manner than in caverns : the 

 absence of light and the scarcity of prey produce in animals which 

 are drawn into them, and succeed in acclimatizing themselves 

 therein, modifications of various kinds. 



The eye, always atrophied, is more or less so according to 

 the species and the individuals of the same species. In certain 

 Amphipod Crustaceans (Ganiniarus, nov. species) it presents varying 

 intermediate states between the almost normal eye, of a blood-red 

 colour and apparently still capable of perceiving certain luminous 

 sensations, and the completely depigmented eye, in which nothing 

 is preserved beyond the external primitive form. Some individuals 

 exhibit varying degrees of atrophy in one eye and the other. 



* Researches made in the Jura in 1894-95 and in the physiological 

 laboratory of the Sorbonue. 



