IV CONTENTS. 



XIII. — A short Description of M. Nachet's Prisms, for the Oblique Illumina- 

 tion of Transparent Objects on the Stage of the Microscope ; with For- 

 mulae for their Construction, and Observations on their Use. By Geo. 

 Shaobolt, Esq. __-.-- -74 



XIV. — Further Observations on the Construction of the Prisms of M. Nachet, 

 for the Oblique Illumination of Transparent Objects on the Stage of the 

 Microscope. By Geobgk Shadbolt, Esq. - - - - 79 



XV. — Note on Nachet's Prism. By M. Nachet. - - - - 82 



XVI. — On the Illumination of Transparent Microscopic Objects on a New 



Principle. By F. H. Wenham, Esq. - - - - 83 



XVII. — On the Occurrence of Non-Gymnospermous Exogenous Wood in the 



Lias, near Bristol. By Henry Clifton Sorby, Esq., F.G.S. - 91 



XVIII. — On the Anatomy of Notommata aurita, an Animal of the Class Roti- 



fera. By P. H. Gosse, Esq. - - - - - 93 



XIX. — On the Minute Structure of the Calcareous Shells of some Recent 

 Species of Foraminifera. By W. C. Williamson, Esq., Professor of 

 Natural History in Owen's College, Manchester. - - - 105 



XX. — On the Occurrence of Parasitic Rotifera in Volvox globator. By Mr. 



John Williams, Assistant Secretary. - 129 



XXI. — The Annular Condenser for the Microscope, a new Instrument, contrived 



and described by George Shadbolt, Esq. ... - 132 



XXII. — On the Femoral Plates or Scales of Zootoca vivipara. By J. B. Spen- 

 cer, Esq. _---.--. 135 



XXIII. — On the Scales of the Viviparous Blenny, (Zoarcus viviparus). By 



John Quekett, Esq. ...-_. 136 



XXIV. — On Ciliary Action in the Spongiadeae. By J. S. Bowerbank, Esq. 137 



XXV. — On the Notommata parasita, Ehrenb., a Rotiferous Animal inhabiting 



the Spheres of Volvox globator. By P. H. Gosse, Esq. - - 143 



XXVI. — On a White Minor for the Microscope. By George C. Handford, 



Esq 147 



XXVII. — On a New Medium for Mounting Fresh or Moist Animal and Vege- 

 table Structures. By H. Deane, Esq. - 149 



XXVIII. — Observations upon Oblique Illumination ; with a Description of the 



Author's Sphaero-annular Condenser. By George Shadbolt, Esq. - 154 



XXIX. — Descriptions of three Species of Marine Zoophytes. By Arthur 



Hill Hassall, M.D., and John Coppin, Esq., M.A. - - 160 



XXX.— On the Sporangia of some of the Filamentous Fresh-water Algae. By 



George Shadbolt, Esq. - - - - - - 105 



XXXI. — On the Sporangia of some of the Filamentous Fresh-water Algae. (Se- 

 cond Paper). By Geobge Shadbolt, Esq. - - - - 108 



