1833.] SEA-PEN. 93 



which is four degrees southward, and therefore with a climate only 

 a very little colder, this same temperature with a rather less ex- 

 treme heat, was sufficient to awake all orders of animated beings. 

 This shows how nicely the stimulus required to arouse hybernating 

 animals is governed by the usual climate of the district, and not 

 by the absolute heat. It is well known that within the tropics, 

 the hybernation, or more properly aestivation, of animals is deter- 

 mined not by the temperature, but by the times of drought. Near 

 Eio de Janeiro, I was at first surprised to observe, that, a few days 

 after some little depressions had been filled with water, they were 

 peopled by numerous full-grown shells and beetles, which must 

 have been lying dormant. Humboldt has related the strange 

 accident of a hovel having been erected over a spot where a young 

 crocodile lay buried in the hardened mud. He adds, "The Indians 

 often find enormous boas, which they call Uji, or water serpents, 

 in the same lethargic state. To reanimate them, they must bo 

 irritated or wetted with water." 



I will only mention one other animal, a zoophyte (I believe 

 Virgularia Patagonica), a kind of sea-pen. It consists of a thin, 

 straight, fleshy stem, with alternate rows of polypi on each side, 

 and surrounding an elastic stony axis, varying in length from eight 

 inches to two feet. The stem at one extremity is truncate, but at 

 the other is terminated by a vermiform fleshy appendage. The 

 stony axis which gives strength to the stem may be traced at this 

 extremity into a mere vessel filled with granular matter. At low 

 water hundreds of these zoophytes might be seen, projecting like 

 stubble, with the truncate end upwards, a few inches above tho 

 surface of the muddy sand. When touched or pulled they suddenly 

 drew themselves in with force, so as nearly or quite to disappear. 

 By this action, the highly elastic axis must be bent at the lower 

 extremity, where it is naturally slightly curved; and I imagine it 

 is by this elasticity alone that the zoophyte is enabled to rise again 

 through the mud. Each polypus, though closely united to its 

 brethren, has a distinct mouth, body, and tentacula. Of these 

 polypi, in a large specimen, there must be many thousands ; yet we 

 see that they act by one movement: they have also one central 

 axis connected with a system of obscure circulation, and the ova 

 are produced in an organ distinct from the separate individuals.* 



* The cavities leading from the fleshy compartments of the extremity, 

 were filled with a yellow pulpy matter, which, examined under a micro- 



