DIASTYLIS. 149 



the sixth furnished with two limbs, ending in double sty- 

 lets; central tail-piece long, produced into a style. A 

 curious genus, the first character in the general appearance 

 of which, as Mr. Spence Bate remarks in his elaborate 

 Paper,* is that of its being a mutilated creature ; the re- 

 duced form of the members generally gives the species the 

 appearance of wanting many of their limbs. Agassiz and 

 others have said that these creatures are the young of 

 certain genera of Macroura, such as Alp/iaus, Palrzmon, and 

 Hippolyte, but Mr. Harry Goodsir has clearly shown that 

 they are adult animals, perfect in themselves; and that 

 they belong to the Stomapoda is proved by Mr. Bate, not- 

 withstanding their being sessile-eyed. 



Mr. Goodsir remarks that the various species swim witli 

 very great rapidity ; and on stopping, they fall to the bottom 

 on the sand or gravel, without attempting to lay hold of 

 anything, seldom using their feet as a means of prehension. 

 He has often placed the point of a needle on their thorax, 

 and pressed them down into the sand ; the animal immedi- 

 ately frees itself, with very little apparent trouble, by means 

 of its tail. The end of this is placed against the needle, 

 with one of the styles on either side of it, and by pressing 



* Ann. and Mag. Nat. Hist., June 1856. 



