Mr Henry Goodsir on some New Crustaceous Animals, S^c. 363 



no scored surfaces, no boulders are to be seen, and this 

 cliange is effected by an ascent of only a few yards ! So great 

 is the contrast, that any one viewing these mountains from a 

 distance, would, in many cases, naturally conclude that their 

 bases and their summits were composed of quite different for- 

 mations. 



Descriptions of some New Crustaceous Animals found in the 

 Firth of Forth. By Henry D. S. Goodsir, Esq., Surgeon, 

 Anstruther. Communicated by the Author. (No. IV.*) 

 With a Plate. 



SECTION I. ON THE GENUS MUNNA. 



While engaged during the end of July last in examining 

 the produce of a day's dredging from the mouth of the Firth 

 of Forth, I observed a crustaceous animal running briskly 

 along the bottom of the vessel, which I at first took to be a 

 small nymphon. On a more minute examination, I found that 

 it was an Isopodous Crustacean belonging to the Famille des 

 Asellotes of Milne Edwards. 



I had applied the name of Thetis as a generic title to this 

 animal, and it was my intention to publish it under this name. 

 Some days afterwards, however, as I was accidentally looking 

 over a few numbers of the Isis for last year (1841), I was both 

 delighted and disappointed to find in the No. VI. for that 

 year, my genus Thttis, fully described and figured by M. 

 Kroyer of Copenhagen under the name of Munna. I, of 

 course, immediately assumed his generic title. 



The only species of this genus which I have examined is 

 remarkable in so far that it possesses pedunculated eyes, which 

 are at the same time quite immoveable, and also in the last or 

 filiform portion of the superior antennae being double. 



The external plate of the abdominal branchia? is extremely 



* This intimates the fourth cf the scries of Original Observations on Bri* 

 tisli Crustaceans, as communicated by the Autlior. 



