73 



mouth of the Tagus. It is known by it's brown- 

 ish-yellow colour, and by it's tentacular which 

 are longer than the body. Several of these sea- 

 nettles were four inches in diameter : their re- 

 flection was almost metallic : their changeable 

 colours of violet and purple formed an agreeable 

 contrast with the azure tint of the ocean. 



In the midst of these medusas Mr. Bonpland 

 observed bundles of dagysa notata, a mollusca 

 of a singular construction, which Sir Joseph 

 Banks first discovered. These are small gelati- 

 nous bags, transparent, cylindrical, sometimes 

 polygonal, which are thirteen lines long and two 

 or three in diameter. These bags are open at 

 both ends. In one of these openings, we observ- 

 ed a hyaline bladder, marked with a yellow spot. 

 The cylinders are longitudinally placed on each 

 other, like the cells of a bee-hive, and form chap- 

 lets from six to eight inches in length. I tried 

 the galvanic electricity on these molluscas, but 

 it produced no contraction. It appears that the 

 genus dagysa, formed at the time of Cook's first 

 voyage, belongs to the salpas (biphores of Bru- 

 guiere) to which Mr. Cuvier joins the thalia of 

 Brown, and the tethis vagina of Tilesius. The 

 salpas journey also by groups, joining in chap- 

 lets, as we have observed of the dagysa*. 



* Account of Voyages undertaken by order of his Britan- 

 nic Majesty, 1789, vol. iii, p. 261. Ann. du Museum, vol. 

 xiv, p. 360. 



