598 Remarks on Marine Animals 



known by sailors as the Portuguese man-of-war) is com- 

 monly met with in tropical seas ; but the largest which I have 

 seen (the air sac measuring about 6 in. in length, and 3 or 

 4 inches in depth) was met with on the edge of soundings in 

 the Channel. 



The following is the account of it which, after a careful 

 examination, I inserted in my note-book. The form of the 

 air vesicle is not unlike that of the human stomach ; having 

 a convex and concave margin ; the former being the lower, 

 and having the tentacula attached to it. The upper is sur- 

 mounted by a crest, bearing some resemblance to the appendi- 

 culse epiploicae of the colon. The vesicle terminates obtusely at 

 each extremity; the beautiful blue or purple tint so delicately 

 suffused over all the membrane here becoming darker, and 

 occasionally, when first taken out of the water, of a bright 

 pink colour. On compression, air escapes from the sac by 

 small orifices at each extremity; a circumstance which in- 

 duced Blainville to regard this as the digestive organ ; an 

 idea contradicted by the uniform absence of any remains of 

 alimentary matter on its internal surface, and by its having 

 no communication with the cavities of the tentacula. It is 

 said to possess orifices opening into the crest ; but, in the 

 specimens which I have examined, I did not detect them. The 

 tentacula are of two kinds ; the short ones, which are very 

 numerous ; and others which, though few in number, attain 

 the length of several feet. The latter consist of a trans- 

 parent and tubular portion, and a blue-coloured string of 

 vesicles. The tubular portion gradually dilates as it ap- 

 proaches the inferior surface of the body of the animal; till, 

 when inflated, it presents an elongated sac ; the other portion 

 remaining unaffected, and, therefore, probably not having any 

 communication with it ; these unite with severaljof the smaller 

 tentacula ; and then pierce the inferior membrane of the sac 

 so as to open by an oblique aperture, covered by a valvular 

 fold of membrane, not into the cavity of the vesicle itself, 

 but into one situated below it, and separated from it by a thin 

 and transparent fold of membrane; the sac thus formed being 

 the digestive cavity : there are five or six of these large aper- 

 tures. The power of stinging, which is so characteristic in 

 the Physalus, is possessed by the tentacula alone, and exists 

 only during the life of the animal ; no irritating property being 

 communicated to fluid in which it is macerated. Towels, how- 

 ever, which have been used to wipe the hands, after touching it, 

 will produce irritation, when applied to the skin, after several 

 Jays. This property is, doubtless, the means by which the fish 

 entangled in its lengthy tentacula are destroyed, they being 



