KEPOKT ON THE DIATOMACEyE. 87 



Podosira, is seen in the centre. The awns are ribbed, gradually attenuated, and bear 

 sparsely disposed but -well-defined thorns along their margins. The valves are perfectly 

 smooth. 



This exceedingly elegant Diatom was found in a preparation made on board the 

 Challenger, and has been named in honour of Mr John Murray. 



Corethron (?) sp. (?). (Plate XXL fig. 6.) 



The singular spherical organism here represented is provided with a raised zone, 

 showing a double row of distinct round granules, and a corona of very fine echinated 

 and slightly arcuate awns. Although it is by no means an easy matter to determine 

 to what this straDge form belongs, I am of opinion, from the fact that it has been 

 found associated with other Corethral frustules, that it is a young form of a species of 

 Corethron, the adult form being reached by the development of a connecting zone. The 

 entire frustule would thus become cylindrical, and be terminated by two convex valves, 

 which would be surrounded at their margin by a corona of granules and by circlets of 

 awns. 



Stephanopyxis, Ehrenb. 



Greville 1 and Professor Walker Arnott, departing from the recognised laws of 

 nomenclature, have desired to substitute the name Cresswellia for that of Stephanopyxis 

 established by Ehrenberg. This substitution, however, has not been generally adopted, 

 notwithstanding the claims that have been advanced in its favour, so that the old 

 designation remains, the genus being defined as follows : 2 — " Frustules simple or united 

 into short filaments, in front view orbicular or oblong, composed of two cellulose valves, 

 each having a crown of teeth, spines or membrane ; central portion obsolete ; lateral view 

 circular." 



Stephanopyxis kittoniana, n. sp. (Plate IX. fig. 5.) 



Frustulis globoso-cylindricis, lineariter punctulatis, et per apicum coronam inter se 

 connexis. Ad insulas Philippinas. 



This organism presents a series of four suborbicular frustules, which are united by 

 means of a corona of capitulate processes, and are granulated or punctated in parallel lines 

 running in the direction of the longitudinal axis of the series. Although some affinities 

 are here presented to the Cresswellia turgida of Greville, for example, in general outline 



^ 1 See Gregory, Diatoms of the Clyde, p. 64, pi. vi. fig. 109; Greville, Micr. Journ., vol. vii. pp. 165, 166, 

 pi. viii. figs. 14-16; Trans. Roy. Soc. Edin.,vo\. xxi. p. 536; Ehrenberg, Die Iufusionsthierehen, p. 165; 

 Monatsber. d. k. Altad. d. Wiss. Berlin, 1844, p. 264; Mikrogeologie, pi. xviii. fig. 4, pi. xix. 13, fig. 6. i 

 2 Pritchard, op. cit, p.- 826. . 



