888 



SYSTEMATIC HISTOEY OF THE INFrSORIA. 



Moiirne deposit. It differs from G. con- 

 strictinn in its more slender form and 

 longer neck. 



O.AnylicumCEi.). — Twice constricted ; 

 bead rounded, rather narrower tliau the 

 oblong inflated middle, w^hicli tapers 

 below into a linear stipes-like base. EM. 

 pl. 15 A. f. 86. Lough Mourne deposit, 

 Ireland. It is allied to G. suhtU-e. Pro- 

 bably both forms shoidd be united to 

 G. constn'cftan. 



G. 3lHsfeIa, EM. pl. 17. 2. f. 37. Fossil, 

 Finland, France; recent, Berlin. We 

 have seen no description of this species. 

 Ehrenberg's figures represent the lateral 

 view elongated, with an oblong median 

 inflation, tapering below into a linear 

 stipes-like base, and above into the ob- 

 long head, which is rounded at the apex. 



2* Friistules imbedded in a shapeless gela- 

 tinous substance. (Gomphonella, Rah.) 



G. oUvaceum (Lj^ngb., E.). — Frustides 

 and stipes forming a gelatinous mass; 

 front view broadly cimeate, with con- 

 spicuous terminal puncta ; lateral valves 

 obovate or subclavate, distinctlv stri- 

 ated. SBD. pl. 29. f. 244. = Gomphonella 

 olivaceum, Rab., j8. atiqusta; G. angusta, 

 K. ; G. angusta, Eab t). p. 61, t. 9. £ 2. 

 Smaller and shorter, with obsolete stride. 

 Europe. 1-2300" to 1-1020". It forms 

 rather large mucous masses of a pale 

 brown colour, which, when dried, be- 

 come pale gTeen with a granulated 

 appearance. 



G. Lenormandi (Chauvin). — Front 

 view narrow, nearly linear ; lateral 

 valves lanceolate acute, with indistinct 

 stripe. KSx\. p. 65. = Sphenella ? Lenor- 

 mandi, KB. pl. 30. f. 61 ; Gomphonella 

 Lenormandi., Rab. Falaise^ France. 

 1-960". Stipes slender^ at length elon- 

 gated. 



Qi. parvulum (K.). — Frustules of the 

 size and form of Spheriella parvula, but 

 stipitate and aggregated into a dense 

 mucous stratum. KSA. p. 65. = Gom- 

 phonella parimla, Rab. 



3 * Frustules in front view curved, with 

 tivo longitudinal sutwe-like lines or 

 vittce. 



G. curvatum (K.). — Frustides in front 

 view cm^ved, with distinct terminal 

 puncta and longitudinal vittae ; lateral 

 valves clavate. KB. p. 85, pl. 8. f. 1-3. 

 = G. minutissimum, E. Common. Eu- 

 rope, Asia, Africa, America, (xii. 9-12 ; 

 XIII. 11.) a, aquatic, = G. curvatum, 

 SBD. ; /3, marine, = G. marinwn, SBD. 



This species differs considerably from 

 the other species of Gomphonema in its 

 curved fi-ustules and longitudinal sutm*e- 

 like strife, and perhaps ought to be sepa- 

 rated from them. It agrees with Rhi- 

 pidophora in the latter character and 

 with Achnanthes in having a median 

 nodide in the ventral or concave valve 

 only. It varies in its mode of growth, 

 according as it is fomid in fresh, brack- 

 ish, saline, or marine waters. The frus- 

 tules are scattered, flabellateiy conjoined, 

 or aggregated in minute cushion-like 

 tufts. The stipes is short, incrassated, 

 and irregidarly branched, or more or less 

 elongated, slender, and dichotomously 

 divided. Professor Smith makes the 

 marine fonn a distinct species, and gives 

 the following differential characters : — 

 G. curvatum : " Stipes elongated, fila- 

 mentous and dichotomous ; stri« 22 to 

 30 in -001'" ; aquatic." G. marinum : 

 '' Stipes incrassated, branching in an 

 irreo-ular manner; striae 35 in -001"'; 

 marine." Professor Smith, however, 

 admits that it is difficidt to distinguish 

 them if we confine our attention merely 

 to the frustules; "but," continues he, 

 "the general appearance of the gTowing 

 plants, arising from the characters of 

 their stipes, is very different, and their 

 habitats are so wide apart that there can 

 be no doubt of their distinctness." We 

 are unable to concur in this opinion ; for 

 our experience is quite different, and, as 

 we stated several years ago, we find the 

 stipes in the marine form more elon- 

 gated than in the aquatic one. " I have 

 attempted in vain to find some specific 

 character to distingTiish the marine form. 

 It is more branched, has a rigid appear- 

 ance, and the striae connecting the puncta 

 on the front surface are strongly marked ; 

 but intermediate specimens occasionally 

 occur, in which all these differences 

 vanish " (ANH. xii.). 



4 * Frustules in lateral view ohovate or 

 clavate. 



t Crested or pointed at the apex. 



G. cristatum (Ra.). — Frontview crested; 

 lateral view obovate, crow^ned with a 

 minute point. SBD. p. 79, pl. 28. f. 239. 

 = G. nasutum, EM. pl. 2. 2. f. 41 ; Sphe- 

 nella ? appendiculata, Perty, p. 203, 1. 17. 

 f. 14. Europe, Asia, America. Stipes 

 nearly simple; frustides in front Adew 

 cimeate, with somewhat rounded angles, 

 crested as in G. coronatum; terminal 

 puncta obsolete. Ehrenberg describes 

 his G, nasuium as allied to G. Augur, 



