12 DONKINj ON DIATOMACE^. 



v^'^y 



12. Amphora Uneolata, n. sp. — Form on V. V. nearly 

 rectangular, slightly convex laterally. Hoop Avitli several 

 longitudinal plicae, finely striated transversely ; valve slightly 

 convex, arcuate on dorsal and linear on ventral margin, with 

 delicate transverse striae ; median line gently curved. Length, 

 about -0030"; breadth of E. V. -0012". 



Hab. Cresswell and Druridge Bay; May to August, 1857 

 and 1858. 



Systephania, Eh7\ 



"Frustules orbicular; disc cellulose, neither septate nor 

 radiate, with an external circlet of spines or an erect mem- 

 brane on the disc, not on the margin ; cellules in parallel 

 rows. The spines are subalate, and not unlike the peristome 

 of a moss.^^ (Pritchard's ' Infusoria,^ 4to edition, p. 832.) 



Such are the characters given by Ehrenberg to a genus of 

 which he has described three species, namely, S. aculeata, 

 distinguished by its few spines (12 to 15) and coarse cellules 

 S. corona, with numerous spines (40 to 50) and finer cellules; 

 (about 11 in '001") ; and S. d'iadema,-\\'\i\\\\wva.Qio\x& incurved 

 spines and still finer cellules (about 13 in -001''). These three 

 species have only been found, hitherto, in a fossil state in the 

 Bermuda earth. 6r" v 'h ) 



13. Systephania Anglica, n. sp. — Valve circular, finely 

 punctate; punctai excentric; spines about nineteen, acute, 

 and curved about the margin of the valve. Diameter, from 

 •0012'^ to -0015". 



I am glad to be able to add this most curious form to the 

 list of British species ; it is the only living representative of 

 the genus hitherto discovered, and from the description above 

 given it will be perceived it differs from S. aculeata, S. corona, 

 and S. diadema in the number and nature of its spines and 

 the minuteness of its areolae. These are only visible, as ex- 

 centric lines of punctae, with a superior English one-fifth or 

 one-eighth objective, and suitable illumination, and wordd, 

 therefore, have been perfectly imdsible by the glasses used by 

 Ehrenberg. 



Hab. Cresswell, May and June, 1858. Although this 

 species is rare, I have examined several specimens from this 

 locality. 



