810 



SYSTEMATIC HISTOEY OF THE INFUSOEIA. 



bars. The most evident distinction, 

 however, is the clavate or capitate lines 

 of the dorsal and ventral margins, those 

 of the latter being longer, fewer, and 



divergent. The septa seem to be rudi- 

 mentary, as in the preceding species. 

 Valves oblong-linear, sometimes cm-ved, 

 with rounded ends. 



GeniLS ENTOPYLA (Ehr.). — Fmstiiles prismatic, compressed, multivalved ; 

 valves contiguous, in a straight, simple series, like the leaves of a book ; 

 internal ones traversed by a large median opening ; outer ones transversely 

 striated, unequal, one entire (not perforated), the other furnished with a large 

 pore at each end. Marine. Entopyla, by its curved form, approaches 

 Achnanthes ; by its tabulate figure it is more akin to Tessella ; but it comes 

 nearer to Biblarium than to any other. Although, in deference to the opinion 

 of Professor Arnott, we have kept Eupleuria distinct fi^om this genus, we 

 doubt the propriety of doing so. From Ehrenberg's comparison of Entojjyla 

 \vith Tessella and Biblarium, and beaiing in mind his peculiar views, it is 

 c\ident that the " internal valves " are the "annuli" of Smith, and the "per- 

 forations of the ventral valve" the blank spaces at each end. Since the 

 opening in the internal valves is stated to be so large as to leave only a thin 

 margin, the septa must be rudimentary. Both Entopyla and Eupleui^ia seem 

 therefore to differ from Khabdonema in their dissimilar valves and rudimen- 

 tary septa, nor are we able to find any character in Ehrenberg's description 

 which enables us to distinguish Entopyla from Eupleuria. 



Entopyla Australis (Ehr.). — Leaves 

 (annuli) about 16 j transverse costaB of 

 outer ones (or valves) 32 to more than 

 40 in nimiber, divided by a median 



flexuose line. ERBA, 1818, p. 42. = 

 Surirella Australis, Ehr. 1843. Pata- 

 gonian guano. 



Genus DIATOMELLA (Grev.). — Frustules quadrangular, forming at first 

 a piano- compressed filament, at length separating ; vittae two, interrupted 

 in the middle and at each end.=Disiphonia, E. Aquatic. Professor Smith 

 doubtfully referred to Grammatophora the Diatom for which this genus was 

 constituted ; but we consider the differences pointed out by Dr. Greville as 

 sufficient, independently of its aquatic habitat, to separate it from that genus. 

 In Grammatophora the septa are formed in the central or connecting portion, 

 arise from the margins of the filament, and are interrupted in the middle. In 

 DiatomeUa they appear to us to arise from a thickened rib connecting the 

 lateral and central portions, and form imperfect diaphragms with three open- 

 ings — one central, the others marginal. We have included DiatomeUa in this 

 family, but, although Professor Smith states that its frustules are annulate 

 and nearest in structui^e to Grammatophora, we are not siu-e it is rightly 

 placed here ; for two puncta exist at each end of the frustule, as in the 

 Fragilariese. 



DiATOMELLA Bolfounana (Gr.). — La- 

 teral view linear or oblong, with rounded 

 ends and 45 fine stri« in -001." GANH. 

 s. 2. XV. pi. 9. fs. 10-13. = Grammato- 

 pJiora ? Balfuuriana, SBD. ii. p. 43, pi. 

 61. f. 3S3.=Disiphoma Amtralis, EM. 



pi. 35 a. f. 7. South Africa, South Ame- 

 rica, Scotland. Front view quadi*angular, 

 vnth. a smooth central portion, separated 

 from the transversely- striated lateral 

 valves by the vittae. (iv. 51, 52.) 



FMHLY VII.— MELOSIREJE. 



Frustules disciform, cylindrical, or globose, simple or united into a filament ; 

 lateral surfaces flat or convex, circular, smooth or with radiating striae, less 

 frequently cellulose, granulate or punctate ; front view with the central por- 

 tion usuallv either obsolete or di^•ided by one or two central furrows. " For 



