BRITISH DESMIDTEyE. 123 



Dolgelley and Penzance, J. R. Rochdale, Mr. Coutes. Weston Bogs 

 near Southampton, Mr. Jenner. 



Falaise, Brebisson. Germany, Kiltziiiff. 



Frond usually smaller than that of Staiirastrum dejectiim ; segments 

 smooth, fusiform or tnmcate on the outer side, separated by a long band-Uke 

 neck which is present also in the dividing frond between the old and new seg- 

 ments; the subulate awns are elongated and straight, and either parallel to 

 those of the other segment or convergent with them. The end view has three 

 or four mammillate and awned lobes. 



Staurasfrum cvsjiidaiion may be known from S. dejection by the elongated 

 baud which connects the segments. 



The sporangium of this species resembles that of S. dejectum, but has 

 fewer spines. 



Length of frond -g-Lj of an inch ; breadth y^Vo '■> breadth at constriction 

 g-gLy ; diameter of sporangium ■^^. 



Tab. XXI. fig. 1 . a,b. fronds with endochrome ; c. frond cUviding ; d. trans- 

 verse view ; e. end view. 



Tab. XXXIII. fig. 10. sporangium. 



3. S. aristiferum ; segments smooth, the lobes in front view 



prolonged into mammillate awned projections which are somewhat 

 constricted at the base ; end view with three or four awned lobes. 

 Dolgelley, /. R. 



Frond smooth, about as large as that of Staurastrum cuspidatum ; segments 

 not separated by a band ; ends usually truncate, but the angles are elongated 

 into mammillate processes, each terminated by a long awn ; end view as in the 

 two preceding species. 



Staurastrum aristiferum may be a variety of S. cuspidatum, but as it has 

 no isthmus between the segments, and the angles in the front view are elon- 

 gated, I have described it as distinct. 



Length of frond ^4y of an inch ; breadth yoVr '■> length of spine ygV^ ? 

 breadth at constriction ^ 5^0 o • 



Tab. XXI. fig. 2. a. front view; h. end view. 



4. B. Dickiei ; segments smooth, subelliptic, turgid ; spines 



short, curved toward those of the other segment ; end view with 

 three slightly inflated mucronate lobes. 



Aberdeenshire, Br. Dickie. Dolgelley, /. R. 



Frond smooth, larger than that of Staiirastrum dejectiim, deeply constricted 

 at the middle ; segments twice as broad as long, eUiptic, but having the outer 

 margin more convex than the inner one ; spines short, curved and converging 

 with those of the other segment. End view with three slightly inflated lobes, 

 which are rounded and mucronate. 



This plant was first sent me by Dr. Dickie, who pointed out its resemblance 

 in a front view to Arthrodesmus convergens. It is however smaller, although 



