402 Mr. W. Thompson on the British Species of 



abundant base in some of the other vegetable tissues, it was 

 probable that this salt was sulphate of potassa. On com- 

 paring the form of microscopic crystals of sulphate of potassa 

 with that of the crystals derived from the pollen, it was found 

 that they were identical ; but in order to determine this point 

 with greater certainty, a solution of oxalic acid was added to 

 the poUenic crystals, which upon evaporation afforded cry- 

 stals having the characteristic form of the binoxalate of po- 

 tassa (fig. 14.). That the potassa existed in the state of car- 

 bonate became probable from the fact, that the water in which 

 the pollen had been macerated did not yield crystals upon a 

 partial evaporation, the carbonate of potassa being deliques- 

 cent. 



Note. — Although the main object of this communication has 

 been anticipated by M. Fritzsche, of whose labours, published 

 in the Transactions of the Petersburgh Academy, our corre- 

 spondent seems to have had no knowledge, it will prove in- 

 teresting to many of our readers, inasmuch as the writings of 

 Fritzsche are little known in this country, and his views are 

 in some degree confirmed by the observations of our corre- 

 spondent, both agreeing in their deductions. M. Fritzsche 

 has not only discovered a third tunic, but even a fourth, which 

 is said to occur, among other plants, in Clarkia elegans, some 

 species of (Enothera, and in Encharidium concinnu. — Edit. 



XL VII. — Observations on several British FisheSj including the 



description of a New Species. By William Thompson, 



Esq., Vice-President of the Natural History Society of 



Belfast*. 



[With a Plate.] 



I. On the British Species of the Genus Monochirus, Cuv. 



By the kindness of Dr. Parnell in supplying me with speci- 

 mens of the Red-backed Flounder of Hanmer, 'Pennant's 

 Brit. Zool.,' (v. iii. p. 313. pi. 48. ed. 1812,) and the Mon. mi- 

 nutuSj Parn., I am enabled to speak decidedly on some points 

 which, in my previous remarks on these species, ' Annals Nat. 



* Read before this Society December 5, 1838, and illustrated by the spe- 

 cimens of which it treated. 



