886 



SYSTEMATIC HISTOKY OF THE INTUSORIA. 



frustule is very crystalline and transparent. It has internally pale-green, 

 almost colourless ova, E. 



Rhizonotia Meh (E.).— The lateral Mdo, EM. pi. 35. 6. f. 14, 15 ?. Swan, 



connecting portions of the progeny in Avon, and Canning Rivers in Western 



self-division mostly forked, 3 to 10. Australia. (\^n. 41.) 

 ERBA. 1843, p. 139. = Rhizosolmia 



EAMILY XYII.— GOMPHONEME.^. 



Erustules in front view cuneate, laterally attenuated at the base, with a 

 median longitudinal line and a central nodule. Mostly aquatic. The Gom- 

 phonemeae differ from the Meridiese and the Licmophoreae, and the cuneate 

 species of SurireUa, by the median longitudinal line and the central nodule. 

 The cuneate form in the front view distinguishes it from the rest of the 

 Diatomacese. 



Genus SPHENELLA (K.). — Erustules in front view cuneate, free, neither 

 stipitate, affixed, nor enclosed in a common gelatinous substance. Aquatic. 

 '' The SpheneUae only diifer from Naviculae in their cuneate form, perfectly 

 similar to that of Meridion, by which, too, the associations {S. angustata) 

 become flabeUiform and quasi-circular ; but they differ by the central nodule 

 of the lateral surfaces. Hence there remains a greater simihtude to the 

 Naviculae ; and the distinctive characters are so slight, that the generic 

 characters of at least two species remain uncertain " (Menegh. p. 411). 



Sphenella glacialis (K.). — Minute; 

 lateral view lanceolate, with subacute 

 ends and very delicate transverse striae. 

 I^. p. 83, pi 3. f. 16. Monte Rosa, 

 Alps. 1-1320". 



S. imrvula (K.). — Minute : lateral view 

 lanceolate, with produced ends, the base 

 subdilated. KB. p. 83, pi. 30. f. 63. 

 France. 1-960". Striae indistinct. It 

 cannot be distinguished from a Navicula, 

 except on a fi-ont view. 



S. angustata (K.). — Minute, flabel- 

 lately conjoined, narrow linear, cuneate, 

 lateral view lanceolate, with obtuse 

 ends. KB. p. 83, pi. 8. f. 4. Germany, 

 France, (xiv. 30.) 1-960". 



S. vulgaris (K.). — Small; lateral view 

 finely striated, dilated at the middle, 

 and ^ tapering to the stout beak-like 



ends. KB. p. 83, pi. 7. f. 12. Germany, 

 France. 1-1020". 



S. ohtusata (K.). — Small ; lateral 

 view smooth, dilated above the middle, 

 with roimded obtuse apices. KB. p. 83. 

 pl.9. f. 1. Prussia, (xiv. 31.) 1-900". 

 Lateral view clavate-lanceolate. 



S. rostellata (K.). — Solitary, smooth, 

 broadly cuneate ; lateral view dilated at 

 the middle, acuminate at each end. KB. 

 p. 83, pi. 9. f. 3. /3. elongata, larger, 

 with produced, obtuse apices. France. 

 1-1820" to 1-336". 



S. ? Italica (K.). — Broadly cuneate ; 

 lateral view obovate, slightly dilated at 

 the middle, and with a transverse me- 

 dian nodule. KSA. p. 63. = Gompho- 

 nema Italicum, KB. t. 30. f. 75. 



Genus GOMPHONEMA (Ag.). — Erustules affixed at the base or stipitate ; 

 in front ^dew cimeate ; laterally attenuated below, with a median longitudinal 

 line and central nodule. " As Cocconema from Cymbella, so Gomphonema 

 only differs from Sphenella by the stipes, on which account species are now 

 referred to Gomphonema which formerly belonged to Sphenella. . . . Kiitzing 

 supposes the Gomphonemae to be at first free, like Sphenella, and that after- 

 wards they affix themselves. ... No direct observation confirms this hypo- 

 thesis ; and it is at least as just to admit the other, that the Sphenellae are at 

 first attached like the Gomphonemae and afterwards become free. Ehrenberg 

 says that the Gomphonemae can become free and again adhere" (Menegh. 

 p. 412). The descriptions apply to the lateral view, unless otherwise stated. 



