OF THE CYMBELLE^. 



879 



Genus SYXCYCLIA (Ehr.) — Friistnles cymbiform, connected in a circular 

 manner ^thin an amorplious gelatinous substance. " Whenever the lateral 

 siufaces are inclined to each other by the different extension of the two pri- 

 mary surfaces, the associated series must be formed circularly" (Meneg.). 



Syncyclia Sal2)a (E.). — Fnistules 

 semi-oval, smooth, mostly connected, in 

 sixes, into short tubes or rino;s : colom"- 



ing matter pale gTeen. E Inf. p. 233, 

 t. 20. f. 11 ; KSA. p. 61. Marine, near 

 Wismar. (vn. 53 ; x. 206.) Length 

 1-2300" to 1-570". When dry, longi- 

 tudinally plicate. 



S. quaternaria (E.). — Fnistules binate 



or quatemate, smooth ; coloming matter 

 golden- or reddish-bro'.%ai. EliBA. 1840, 

 p. 22 ; KSA. p. 61. Marine. Europe. 

 1-864". 



SiJecies Jmotoi to us only by name. 



S. granulata (E.), Georgia ; S. Am- 

 phora (E.), Palestiae. 



Genus EXCYOXEMA (Ktitz.). — Fnistules cymbiform, arranged in longi- 

 tudinal series within submembranous tubular filaments. Valves divided 

 unequally by median line and nodules. " Encyonema differs from Schizo- 

 nema and other frondose genera of Diatomaceae in the form of its fnistules, 

 a single frustule resembhng one of Cymbella or Cocconema. It is more 

 probable that some bodies, which are reaUy congeries of the ova of certain 

 insects, will be at first sight classed with Encyonema ; but these ova, although 

 cymbiform and arranged in longitudinal series, are neither siliceous nor 



striated The lateral surfaces of the frustule, being convex, are observed 



in the front view, in which also the fnistules are quadrilateral, with two 

 puncta at each end. These puncta are less easily discerned in the dorsal 

 view, and the dorsum is longitudinally convex. The lateral view is semi- 

 eUiptic, with numerous transverse striae, which are interrupted, as in Cocco- 

 nema, by a longitudinal pellucid hue" (Ralfs). Professor Smith says that the 

 frustules of Encyonema, even when removed from the frond, may be distin- 

 guished from those of CymbeUa, "as the terminal nodules of the median line 

 in CymbeUa are placed at the extremities of the valves, while in Enej^onema 

 they are removed to some distance above, and occupy a place nearer the 

 central nodule." 



ExcYONEMApros2;>-«^w;/i (Berk., Ralfs). 

 — Filaments subsimple j valves with 

 rounded, mostlv incurved ends; strise 

 18 in -001". Leng-th -0016" to -0024". 

 Ealfs, ANH. 1st ser. x\-i. pi. 3. f. 3 ; 

 KSA. p. 61; SD. ii. p. 68, pi. 54. f. 345! 

 = Momnna j^^'ostratum, Berk BA. pi. 4. 

 f. 3 ; Schizo)iema prostratum, Grev BFl. 

 p. 414 ; Encyonema paradoxwn, E Inf. 

 p. 237 ; Gloeonema Leihleini, Ag CD. 

 p. 31 ? Em^ope, Asia, America. The 

 valves have a depression beneath each 

 apex ; sometimes the depression is very 

 slight, at others so deep and notch-like 

 that the ends become rostrate. The 

 former condition is the E. imradoxum of 

 Kiitzing. {xtl. 49 ; xiv. 22.) 



E. Auersicaldii (Rab.). — Valves with 

 ver}^ convex dorsum, slightly gibbous 

 venter, and contracted, produced, obtuse 

 ends ; striae 11 or 12 in -001". Rab D. 

 p. 24, pi. 7. f. 2. Leipzig. 



E. ccespitosum (K.). — Filaments erect, 

 tufted, much interwovou ; valves with 



convex dorsum, slightly tumid venter, and 

 straight, slightlv produced, obtuse ends ; 

 stri« 24 in -001". KSA. p. 61 ; SBI). i. 

 p. 68, pi. 55. f. 346.=^. jJrostrafitm, KB. 

 p. 82. Europe. The fi'ustules are 

 smaller than those of E. 2^i'ostratum. 



E. triangulum (E., K.). — Valves with 

 very convex, gibbous dorsum, slightly 

 convex venter, and produced, acute 

 apices. KSA. p. 62. = Gl<jeonema trian- 

 gulum, ERBA. 1845, p. 77 ; EM. t. 35 a. 

 7. f. 10. River Niagara. Dorsum so 

 turgid as to give the valve a ti'iangular 

 outline. " It is a very remarkable cir- 

 cumstance, that I often found two differ- 

 ent sorts of frustules in the same tube 

 — one very delicate and straight like a 

 Naunema, the other the large curved 

 kind. Even to the present moment I 

 cannot explain this phenomenon ; for both 

 sorts were in considerable quantities and 

 quite free, and therefore it is difficult to 

 suppose one a parasite " (E.). 



E. Sinensis (E.). — Valves oblong, 



