ARCHER, ON DESMIDIACE.E. 237 



and depressed, not elevated and conic. It is true that Pro- 

 fessor de Bary (' Untersuchungen fiber die familie der Con- 

 jugaten,' Taf. VI, 49 a b) alludes to a Cosmarium called by 

 him Cosmarium orbiculatum (Ralfs), which, I apprehend, is 

 actually the species now described, but, with great deference, 

 I think he is wrong ; this form differs quite from C. orbicu- 

 latum (Ralfs), as much, indeed, as C. bioculatum (Breb.) does 

 from C. moni.Uforme (Ralfs). Assuming that I am right in 

 the conjecture that the present species is identical with that 

 alluded to by De Bary under the name of C. orbiculatum 

 (Ralfs), the sporangium has been provisionally described in 

 the foregoing specific characters, taken from the figure given 

 by that observer, although I have not myself met it con- 

 jugated. 



As to other granulate species, so far as I am aware, it needs 

 only to contrast this form with C. pluviale (Breb.), with 

 which it agrees in being compressed, and in the constriction 

 not forming a linear notch, but it differs in the form of the 

 segments, which, in the species just named, are nearly as 

 broad as long, sub-ovate or sub-orbicular, ends rotundato- 

 truncate ; whereas, in the species in question, the segments 

 are broader than long, elliptic, and ends rounded, the con- 

 striction forming a short neck. Of the smooth species, it 

 most nearly approaches C. bioculatum (Breb.) in form, but 

 the granulate surface of the present species at once dis- 

 tinguishes it. The same circumstance, as well as the want of 

 the solitary superficial projection on each front surface of the 

 segments, separate it from C. phaseohis (Breb.). 



I am not aware of any other species with which it seems at 

 all requisite to compare the present form, nor does there in- 

 deed appear to me any danger, Avith proper attention, of con- 

 founding it with any of those I have mentioned. This has 

 occurred to me for three or four successive years, and I have 

 no doubt of its distinctness. I have several times been asked 

 the name of this species : to afford a more satisfactory answer 

 than hitherto, the next time the question may be put to me, 

 I have no hesitation in assigning one to this pretty little 

 species. 



On a former occasion ('Nat. Hist. Rev./ vol. v, p. 251) I 

 had the pleasure to name a species, for the ample reasons 

 there given, after my friend, George Porte, Esq. I was not 

 then aware that Professor De Bary, in Germany, had antici- 

 pated me ; consequently, my name for the species alluded to 

 fell to the ground, and with it much of the compliment I had 

 intended. To restore the latter, I trust the present attempt 

 may be more successful. 



