NOTICE OF THE GENUS TETRAPEDIA, ETC. 353 



gelatinous envelope, and forming an unequally rounded glo- 

 bose family. Gomphosphperia thus would seem to form, to 

 a certain extent, a parallel amongst Chroococcacea) (Phy- 

 cocliromaceas) to Oocardium amongst Pallmelacese (Chloro- 

 phyllacese) . 



It does not appear, then, until the genus Tetrapedia was 

 founded by Professor Reinsch,' for two new and singular 

 exceedingly minute Chroococcaceous forms, that examples of 

 specially figured cells were known in this family of Algae. 

 Here we have unicellular Chroococcaceous plants existing 

 quite free and unattached, and, therefore, in no way acted 

 upon by mutual pressure, or capable of being modified in 

 outline by any mechanical exigency of position of growth, 

 and at same time ofiering very characteristic and even com- 

 plex figures. Inasmuch, therefore, as I apprehend Professor 

 Reinsch's work must be but little known in this country, 

 and as the specialities of his form seem not yet clear, upon 

 which, possibly, observers with us, should they encounter 

 them, might be able to assist in throwing light — and, further, 

 inasmuch as I am myself acquainted with two other figured, 

 but less complex, also very minute forms, clearly of similar 

 nature, though not absolutely fitthig into the genus, as cha- 

 racterised by Reinsch — for these reasons it has appeared to 

 me that a notice thereof might find a fitting place in these 

 pages, accompanied by a jn'oduction of Reinsch's, as well as 

 by a sketch of my own forms (PI. XXI) , and (although no 

 further light can be shed upon them than that " there they 

 .are") become, at same time, a not Avholly unwelcome contri- 

 bution to English readers. 



Perhaps, before endeavouring to convey an idea of my two 

 less striking but new forms, it would be best to reproduce 

 Reinsch's Latin description of his genus, and of his two 

 forms falling thereunder, examples of one of which I have 

 also once myself met with in a gathering made in County 

 Westmeath. It is as follows : 



Class, Phycochromacece. 

 Family, Chroococcacem. 

 Genus, Tetrapedia (Reinsch). 



Cellulae solitariee aut rarius consociatione individuorum 

 plurium familias ex cellulis binis, quaternis aut 16is exstitu- 

 tas constituentes, in sciagraphia quadraticee, cellula singula 



1 ' Die Algenflora des niittleren Theiles von Frauken,' by Professor Paul 

 Reinsch, Kiiinberg, 1867, p. 37, t. ii, fig. ii, and t. ii, fig. iv. Also in 

 the authors Memoir "Despeciebus generibusque nonnullis novis ex AU 

 garum et Fungorum Classe" (1867, p. 30, t. i, fig. A i; ex vol. vi, 

 'Act. Societ. Senckeub.'}. 



VOL. XII. NEW SER, C C 



