306 PROCEEDINGS OF SOCIETIES. 



form as defined by Ralfs as Cosm. Brehissonii, with Jacobsen's 

 far smaller and very different form. One can only marvel how 

 he could think for one moment of regarding these two widely 

 distinct forms as falling under one and the same species ; upon 

 such principles it would be useless and almost hopeless to arrive 

 at any clear idea of the forms that really exist and " what's 

 what." If Ealfs could be proven wrong in annexing the name 

 Cosmarium Brehissonii to the handsome form now so well known 

 by that designation, why be it so, and give it a new name ; but 

 Jacobsen's wants a name of its own, and one would fancy it 

 would only lead to confusion to call the latter Cosm. Bre- 

 hissonii. But why not let well alone? "Whether the form now 

 exhibited be one and the same with Jacobsen's, would probably 

 be very difficult of determination in the absence of an authentic 

 specimen from Jacobsen himself; it did not seem thoroughly 

 to agree with it, yet there seems no published figure coming 

 closer to it. Be that as it may, it might just as well be 

 made a "variety" of Cosm. tetrepthalimum, biretum, margari- 

 tiferum, &c., as of Cosm. Brehissonii (as commonly understood), 

 which stands very well indeed on its own basis. The form ex- 

 hibited was under medium size or small ; constriction deep, linear ; 

 lower angles very acute, rectangular ; lateral margins for a time 

 vertical, then arching round to form very broadly rounded upper 

 angles, which merge into the subtruncate upper margin ; lateral 

 margins irregularly serratulo-undulate, the crenatures so formed 

 becoming somewhat smaller upwards, presently becoming obso- 

 lete ; on upper angle and upper margin nearly smooth ; front 

 surface granulate, granules faint and scattered ; end view fusi- 

 form-elliptic. 



