116 



object is not removed, dash out again in full activity of body, then 

 return to the rotundiform position, and there remain for a short 

 period apparently exhausted by tbeir effbrts. But on the cessation 

 of the irritatfng cause, the animal quietly resumed its original po- 

 sition, perhaps dropping one or t\vo of its -vvearied fins according 

 as its own sensations of ease or comfort might dictate. 



" When nothing irritated this tender mollusk, it would remain 

 tranąuilly floating upon the surface of the water with scarcely any 

 movement but that M-hich proceeded from the undulating movements 

 of the digitated estremities of the fins, as w'ell as an occasional 

 slight twisting motion of the šame organs. 



" I f eit much interest in the beautiful display of a circulating fluid 

 on the dorsal surface of these animals, \vhich \vas alForded me by 

 the assistance of a microscope. Through the semi-transparent mem- 

 brane of the back, a fluid could be readily perceived close to the sur- 

 face, evidently flowing in two directions, one taking a course down- 

 wards, and the other retuming upwards; but I was unable to di- 

 stinguish two distinct vessels for these separate actions. 



" These animals seemed to be very torpid in their movements, 

 although sometimes, when floating upon the water, they -vvould 

 be seen busily engaged in moving their fins about, but those actions 

 ■\vere soon suspended and their fins were sufFered to hang lazUy 

 down, as if fatigued ^yith the short exertion, w'hich did not movė 

 them one inch about the glass of water ; and even when the little 

 indolent creatures did take the trouble to movė themselves from one 

 side of the glass to the other, it was effected by a tardy motion, 

 stirring themselves first 'vvith one fin and then with the other, ac- 

 cording as circumstances might reąuire. 



" I placed some small specimens of Porpita in the glass of water 

 containing the Glauci, to observe if they would attack them; for 

 some time one of the Glauci "nas close to a Porpita and was even 

 annoyed by the tentacula of the latter touching its back, yet the 

 Glauctis bore this, although witii the usual characters of impatience, 

 yet without attempting to attack it. At lašt it seized the Porpita 

 between its jaws, and by aid of a powerful lens, an excellent oppor- 

 tunity Avas afforded me of closely watching the devouring process, 

 \vhich was effected b^^ an apparently sucking motion; and at this 

 time all the digitated processes of the fins ^ere floating about, as at 

 other times Avhen the animal was at ręst; but 1 did not observe, in 

 one single instance, that they "vvere of any use to the animci], either 

 to aid in the capture or to securely hold their prey when in the act of 

 being devoured; for the animal seems to depend merely upon the 

 mouth in capturing its prey, as in this and other instances, -vvhich 

 I had opportunities of observing, they seized their prey instantly 

 with the mouth, and held it by that power alone, Avhilst by a kind 

 of sucking motion the prey 'vs'as devoured. The digitations may 

 therefore only be regarded as appendages to the fins to aid the ani- 

 mal perhaps in the direction of its movements, as it \vas observed 

 that they turned and twisted them about during the progressive mo- 



