OF THE AC^^^\NT^E^. 



873 



nute ; valves ventricose, with rostrate 

 ends. KB. p. 75, pi. 3. f. 21. Falcatella 

 delicatula, Rab D. p. 46, t. 5. f. 4. Sub- 

 marine. Germany, (xiv. 16.) 1-1680". 



A. cryptoceplialum (Nag.). — Valves 

 lanceolate - linear, with the subacute 

 apices attenuated or obsoletely capitate. 

 Nag. in KSA. p. 890. S^^-itzerland. 



A. lineare (S.). — Frustules minute ; 

 valves linear, obtuse, upper with median 

 line only, lower with median line and 

 nodules; sti-ise obscure. SBD. ii. p. 31, 

 pi. 61. £381. Freshwater. Scotland. 



A.JlexeUum (K., Breb.). — Valves ob- 

 long, with gibbous middle and very 

 obtuse ends ; median line sigmoid. Breb. 

 KSA. p. 54. = Cymhella {?)JlexeUa, KB. 

 p. 80, pi. 4. f. 14 ', Rab D. p. 23, pi. 7. f. 15 ; 



Achnanthes Bavariea, ERBxA.. 1853, p. 

 526; Cocconeis Thwaitesii, SBD. i. p. 21, 

 pi. 3. f. 33. Fresh water. Europe. 

 1-650" ; striae indistinct ; front view 

 ^vdth genuflexed venter, convex dorsum, 

 obtuse ends, and a notch-like punctum 

 at the middle of the lower margin. 



2 * Frustules large, distinctly striated. 



A. coarctatum (Breb.). — Valves elon- 

 gated, linear- oblong, constricted at the 

 middle, with slightly attenuated, obtuse 

 ends, striae distinct. Breb. in SBD. ii. 

 p. 31, pi. 61. t. 379. = Achnanthidimn 

 Otrantinum, Rab D. p. 25, pi. 8. f. 3 ; 

 Achnanthes binodis, EM. pi. 34. 5 B. f. 1 ?. 

 Fresh water. Europe, Africa, America. 

 (VII. 41.) 



Genus ACHNANTHES (Bory St.-Vinc, Ag.). — Fnistules bent, solitary 

 or aggregate, attached to a stipes, a central nodule in the lower or ventral 

 valve only. The fmstiiles are bent downwards ; so that the ui)per margin is 

 convex, the lower one concave. In some species the lateral portions are 

 turgid, the central one looking like a band between them ; in others they do 

 not enter into the front view. The superior lateral surface differs from the 

 lower in the absence of the central transverse pellucid line and central nodule, 

 the latter appearing like a punctum in the front view. A median longitu- 

 dinal line is present in both valves. In their obscure striae " three species 

 {minutissima, exilis, parvula) present great analogy of form with the pre- 

 ceding genus. In one of these (parvula) there is wanting the characteristic 

 angular bending, for which reason it becomes very similar to Odontidium 

 and Diadesmis. The other species (striatce) differ only by verj' slight cha- 

 racters fi'om each other " (Meneg.). 



* Valves divided by two constrictions 

 into three lobes. 



Achnanthes ventricosa (E.). — Valves 

 divided by two constrictions into three 

 oblong inflations ; apices roimded ; striae 

 distinct. EM. t. 1. 2. f. 9 ; t. 1. 3. f. 18, 

 ld.=3Ionoyra?nma ventricosa, E. Asia, 

 Africa, America. 



2 * Valves distinctly striated, not three- 

 lobed. Ifarine. 



t Valves costate. 



A. longipes (Ag.). — Gregarious ; valves j 

 elliptic-oblong, costate, with monilifonn | 

 striae between the costae. ASA. p. 1 ; I 

 KB. p. 77, ph 20. f. 1; SBD. ii. p. 26, 

 f. 300. = Conferva stipitata, Eng. Bot. 

 t. 2488 ; A. Carinichaelii, Grev. in Br. Fl. 

 ii. p. 404. {yii. 42.) On Marine AlgJB. I 

 Em-ope, America. Few-pointed ; frus- I 

 tules large, with stout elongated stipes ; I 

 front view turgid, with convex dorsmn. ; 

 1-570" to 1-120". I 



2 1 Valves striated, but not costate. 



A. brevipes (Ag.). — Gregarious ; valves 

 oblong, with attenuated acute ends ; striae 

 distinct, monilifonn, 20 in -001"; stipes 

 stout, short. Ag CD. p. 59 ; SBD. ii. p. 27, 

 pi. 37. f. 301. Marine. Em-ope, Ame- 

 rica.^ (x. 199-202.) Frustules large, very 

 turgid in front view, with convex dor- 

 sum. 1-860" to 1-180". 



A. salina (K.). — Frustules striated, 

 very turgid, obtuse-angled, genuflexed, 

 with slightly notched venter ; valves 

 broadly linear, ^dth cuneate ends ; striae 

 punctated ; stipes very short, thick. KB. 

 p. 77, pi. 20. f. 5. Salt marshes. Europe. 

 Differs from A. brevipes only in its more 

 linear valves and cimeate ends. Professor 

 Smith was probably right in uniting 

 them. 



A. intermedia (K.). — Few-jointed ; 

 frustules striated, obtuse-angled, turgid; 

 valves sublinear, with acutely cuneate 

 ends; stipes short, distinct, fine. KB. 

 p. 76, pi. 20. f. 6. On Enteromorpha 

 intestinalis. Germany, France. Smaller 



