or THE EUNOTIEuE. 



'G5 



Genus AMPHICIMPA (E.). — Frustules in lateral view Innately curved, 

 having per\ious transverse stria) and denticulated margins. Amphicampa is 

 closely allied to Eunotia and Himantidium, but differs in ha\ing teeth on 

 both margins. 



Amphicampa mirahilis (E.). — Valves l EM. pi. 33. 7. f. 2. = A. Emca, EM. 

 linear, with rounded ends ; dorsum with pi. 33. 7. f. 1. Mexico, (iv. 5.) 

 six or seven teeth, and venter with five, j 



Genus HIMAjS'TIDIUM (E.). — Frustules united into filaments or tables"; 

 lateral view arcuate or lunate, transversely striated. If all the species in 

 Himantidium formed ribbon-like filaments, there would be no difficulty in 

 distinguishing it from Eunotia ; but this is not the case, and Kiitzing has 

 well said, " It must be noticed that in many species of Himantidium the 

 individuals are not always united into a band, and therefore the generic 

 character is very variable and stands on a weak foundation." Professor 

 Smith observes that " there is no mark to distinguish the valves of the two 

 genera unless it be in the character of the stria?, which in Eunotia arc 

 radiate and in Himantidium parallel." If the strise were indeed always 

 radiate in the one genus and parallel in the other, a valuable diagnostic 

 mark would be fui-nished; but, unfortunately, the convergent stria? occur 

 only in those species of Eunotia which have a strongly convex upper margin. 

 In the front view Himantidium resembles the Eragilarieae, but in that family 

 the lateral view is not arcuate. 



* Dorsum simple. 



Himantidium pectinale (Dillwyn, K.). 

 — Frustides united in long filaments; 

 valves linear, arcuate, with flattened 

 dorsum suddenly sloping to the obtuse 

 apices, and slightlv concave venter ; 

 strise 27 in -001". 'KB. t. 16; SBD. 

 p. 12, pi. 32. £ 280. = H. minus, KB. 

 p. 39, t. 16. f 10 ; H. strictum, Rab 

 Diat. t. 1. f 1 c ; Fragilaria pectinalis, 

 Lyngb. ; Fragilaria grandis, E Inf. in 

 part ; Eunotia depressa, EA. p. 126. 

 Europe, Asia, Africa, and America. 



H. Soleirolii (K.). — ^^alves lunate, with 

 evenly convex dorsum, concave venter, 

 and rounded ends; striae 30 in -001". 

 KIB. p. 39, t. 16. f. 9 ; SBD. vol. ii. p. 

 13, pi. 33. £ 282. = Himantidium Faba, 

 EM. t. 1. 2. £ 3 ; Eunotia Faba, E. in 

 part ? Europe and Africa, (xiv. 13.) 

 It might have been preferable to have 

 adopted Ehrenberg's name for this spe- 

 cies, since it is evident that the JI. 

 Soleirolii of Kiitzing was intended to 

 include all forms with internal siliceous 

 ceUs, and his figures of the valves belong 

 to another species. 



H. parallelum (E.). — Valves linear, 

 stronglv striated, curved, ^\ath simply 

 rounded ends. EM. pi. 14. £ 58. = Eu- 

 notia parallela, EA. p. 126. Europe, 

 Asia, Afi-ica, and America. 



H. monodon (E.). — Frustules large, 



few together ; valves arcuate, with some- 

 what gibbous dorsmn, and obtuse, shghtly 

 produced apices ; strioe 34 in -001". EA. 

 p. 129, t. 4. = Eunotia monodon, EM, 

 many figm-es. SBD. vol. i. pi. 2. £ 16. 

 Common. Europe, Asia, Australia, Africa, 

 and America, (xv. 16, 17.) 



H. prceruptum (E.). — Valves striated, 

 elongated ; dorsimi very convex, with a 

 notch-like depression near the dilated 

 truncated apices. = Eunotia preerupta^ 

 EA. p. 126, & M, several figures. Asia, 

 Australia, and America. According 

 to Ehrenberg's figures, its valves scarcely 

 differ from those of H. monodon, 

 except by their more truncate apices, 

 and can scarcely be placed in another 

 genus. 



H. Arcus(Fi.). — Valves linear, arcuate; 

 dorsum sinuated towards the rounded 

 dilated apices. ERBA. 1840, p. 17, & 

 M, many ^gm:es.=Eu7iotia Arcus, EM. 

 Europe, Asia, Australia, Africa, and 

 America. /3, extremities gradually taper- 

 ing, = H. attenuatum, Bab Diat. p. 19, 

 t. 1. £ 10. Germany. 



H. gracile (E.). — Valves slender, nar- 

 row-linear, slightly arcuate, with obtuse, 

 somewhat recm-ved extremities. EA. 

 p. 129, t. 2 ; SBD. vol. ii. p. 14, pi. 33. 

 £ 285. = Eunotia uncinata, EA. p. 126, 

 & M. pi. 15 B. £ 23. Europe, Asia, 

 Australia, Africa, and America. Habit 

 of H. Arc/us, but more slender, E. Striae 

 27 in -OO'l". S. 



