Sin 9 = 



179 



If a tangent be drawn from it to tlie sphere, and Q be the 

 semi-aperture, it is manifest — 



r _ ^ 



3 ~ 3 ' 



y 



Full aperture or 2 = S3°"38' very nearly. 



(3) The reduction of aperture increases the breadth of the 

 Wack annulus, until, if there is sufncient penetration, its 

 apparent breadth, for direct ilkiminating rays, may be made 

 to appear to be one third of the apparent diameter of the 

 bead, and even much greater. 



Index to Diatoms figured in the ' Quarterly Journal of 

 Microscopical Science,' from 1853 to 1867. By 

 C. J. Muller, Esq. 



Achnanthes — 



Gregoriana, 1859 ; pi. 6, Journ. 



angustata, 1859; pi. 8, Journ. 

 1S60; pi. 1, Journ. 



costatus, I860; pi. 1, Journ. 

 Actinocyclus — 



sedenarius, 1854; pi. 6, Trans. 



triradiatus, 1S5S; pi. 3, Journ. 



areolatus, 1860 ; pi. 5, Journ. 

 „ 1860; pi. 6, Journ. 



Actinoptyclius — 



minutus, 1866 ; pi. 1, Trans. 

 Actinosphoenia — 



spleiidens, 1860 ; pi. 6, Jouru. 

 Acliuiscus — 



Sirius, 1860 ; pi. 7, Trans. 

 Antiuodijcus — 



Barbadensis, 1863 ; pi. 4, Trans. 

 Amphitetras — 



arisata, 1854; pi. 1, Trans. 



tessellata, 1854; pi. 1, Trans. 



crux, 1859 ; pi. 9, Journ. 



antediluvianum,lS59 ; pi. 9, Journ. 



minuta, 1861 ; pi. 9, Trans. 



radiata, 1862 ; pi. 2, Trans. 



punctata, 1862; pi. 2, Trans. 



producta, 1862 ; pi. 9, Trans. 



nobilis, 1865 ; pi. 9, Trans. 



elegans, 1866 ; pi. 2, Trans. 

 Amphora — 



arcus, 1855 ; pi. 4, Journ. 

 „ 1857; pi. 1, Trans. 



Amphora {continued) — 



incurva, 1855 ; pi. 4, Journ. 



angularis, 1855 ; pi. 4, Journ. 



rectangularis, 1857; pi. 1, Trans. 



elegans, 1857; pi. 1, Trans. 



plicata, 1857; pi. 1, Trans. 



biseriata, 1857; pi. 1, Trans. 



lineata, 1857; pi. 1, Trans. 



obtusa, 1857; pi. 1, Trans. 



erassa, 1857; i)l. 1, Trans. 



Grevilliana, 1857; pi. 1, Trans. 



sulcata, 1858 ; pi. 3, Journ. 



membranacea, 1858; pi. 3, Journ. 



litoralis, 1858; pi. 3, Trans. 



arenaria, 1858 ; pi. 3, Trans. 



ocellata, 1861 ; pi. 1, Journ. 



naviculacea, 1861 ; pi. 1, Journ. 



lineolata, 1861 ; pi. 1, Journ. 



Sarniensis, 1862 ; pi. 9, Trans. 

 Ampbiprora — 



vitrea, 1855; pi 4, Journ. 



minor, 1857 ; pi. 1, Trans. 



lepidoptera, 1857; pi. 1, Trans. 



recta, ]857; pi. ], Trans. 



n. sp., 1857 ; pi. 1, Trans. 



conspicua, 1861 ; pi. 10, Trans. 



oblonga, 1863; pi. 1, Trans. 

 Arachnoidisciis — 



Grevilleanus, 1865 ; pi. 5, Trans. 

 Asteromphalus — 



flabellatus, 1859 ; pi. 7, Journ. 



elegans, 1859 ; pi. 7, Journ. 



