222 HISTORY OF BRITISH CRUSTACEA. 



Arcturus intermedius, Goodsir,* sp. — Resembles the 

 last, but its prominent parts are more boldly thrown out : 

 upper antennas are longer than two first joints of the lower; 

 a double row of tubercles on each side of the body. Length 

 from four to five lines; straw-coloured, spotted with brown. 



Firth of Forth (Mr. H. Goodsir). 



Arcturus gracilis, Goodsir, sp. — Slender, quite smooth; 

 upper antennas nearly as long as the three first joints of the 

 lower. Dirty- white, with brown spots. Length, seven 

 lines. 



Firth of Forth, off Anstmther (Mr. H. Goodsir). 



Mr. Goodsir has had all the species alive. They select a 

 branch of coralline and keep that branch exclusively to 

 themselves, defending it with the greatest vigour against all 

 intruders ; they use the true thoracic feet to fix themselves. 

 Their natural mode of progression is swimming. " It is 

 amusing to see one of these animals resting, in an erect 

 posture, on a branch of coralline, by means of its true tho- 

 racic feet, waving its body backwards and forwards, throw- 

 ing about its long inferior antennse, and ever and anon 



* Goodsir, " On two Dew species of Leachia," Edin. New Phil. Journal, 

 Oct. 1841. Mr. Goodsir restricts the name Arcturus to the Arctic species, 

 and applies Dr. Johnston's name Leachia to the three British species. 



