600 Marine Animals met voith during a Sea Voyage. 



outer of which are pointed ; the inner have acetabula, or 

 suckers, at their extremity; and seem, from partaking of the 

 discoloration of the stomach, to communicate with that organ. 

 In the centre of these is situated a tubular mouth, leading 

 into a simple stomach; and external to this lie the delicate 

 cords I have described as nervous. The plates are firm and 

 resistant, the horizontal one appearing to be composed of se- 

 ries of imbricae concentric to the apex, from which, also, radii 

 extend towards the circumference of each. The plates would 

 appear to consist of two laminae ; the upper portion of the hori- 

 zontal one being elevated, to form the vertical plate; while the 

 lower is continued across ; since they separate freely, leaving 

 glistening surfaces in the direction which would result from 

 such an arrangement. When off Tristan d'Acunha, we saw 

 numerous Vellellae, almost all of which had become the nu- 

 cleus to which common barnacles (the Pentalismus Annatifa) 

 had attached themselves ; the valves, however, covering their 

 cirri consisting only of cartilage, without any intermixture of 

 carbonate of lime. 



It is not, however, the Acalephae alone which fall in our way 

 at sea; there are numerous animals of the order Tunicata, 

 the first division of Cuvier's class of Molliisca, which are met 

 with. These animals show considerably greater advancement 

 in the chain of animal organisation than those we have de- 

 scribed : they are enclosed in an elastic membrane, with two 

 openings, by which the water is made to circulate through it, 

 to afford them nourishment, and effect the aeration of their 

 fluids: they have ciliated branchiae, an oral and anal aper- 

 ture, a stomach, sympathetic ganglia, and a circulatory appa- 

 ratus. To this class of animals belongs the beautiful Pyroso- 

 ma; consisting of an aggregate of minute, globular, transparent 

 bodies, enclosed in a common sheath, open at each extremity, 

 through which the water circulates. Its motions are effected 

 by the expansion and contraction of each animalcule ; and, 

 during these, it throws out the most brilliant flashes of phos- 

 phorescence. Early one morning, when off Cape Lagullas, the 

 sea was literally covered by long strings of what I then took to 

 be some species of spawn, but which I now recognise as masses 

 of one of the animals of this class, the Salpae; probably the 

 Salpa confederata, since it closely resembled the specimen of 

 this animal preserved in the museum of the College of Sur- 

 geons. These cords, often nearly a yard long, presented a 

 curious serpentine movement from the slight swell of the sea, 

 for it was nearly calm. Upon examination, they proved to 

 consist of transparent ovoid masses, about the size of a nut, 

 strung together in such a way as to give a beautiful beaded 



