Mme. J. Power on the Habits of various Marine Animals. 335 



have only just discovered them amongst some old papers ; I 

 therefore hasten to lay the following observations before you. 



Having procured several living specimens of Bulla lignaria, I 

 opened their digestive sacs, to ascertain what their nourishment 

 consisted of; in almost all 1 found small specimens oi Dentalium 

 entale. I then set myself to investigate the mode and the time 

 which they employ to digest the Dentalia. 



On the loth July 183G I placed some specimens of Bulla 

 lignaria in a ' cage/ without providing them with food, and on 

 the IGtli I placed close to my BulUe a quantity of Dentalia ; 

 when, by not losing sight of the Bullae, I saw that they devoured 

 the Dentalia. An hour after their repast, I took one of them, 

 ojiened its digestive sac carefully, and found in the alimentary 

 canal, extending in a straight line from the mouth to the orifice 

 of the digestive sac, five Dentalia placed side by side, and their 

 points were already digested for a distance of 2 millimetres in 

 length. The digestive sac of the Bulla consists of two very hard 

 pieces, supported by membranous and elastic ligaments, which 

 allow the movement of trituration, and this acting from right to 

 left, and facilitated by the gastric juice, reduced the Dentalia 

 into a nutritive pulp ; they slip by little and httle and altogether 

 into the sac, in proportion as the animal triturates them. This 

 is the only food of the Bulla lignaria. 



Two hours after my first observation, I took a second Bulla : 

 its alimentary canal only contained four Dentalia, which were 

 more than half digested. Two hours afterwards I took a third : 

 of six Dentalia which it had in its alimentary canal, there only 

 remained a length of 3 millimetres. The last that I opened had 

 employed seven hours in its digestion. 



From the observations which I have made, I have ascertained 

 that some Bulla digest more rapidly than others. 



On the Nourishment and Digestion of the Asterias (Astropecten) 

 aui'antiaeus. 



On the 20th July 1836, I placed three large specimens of 

 Asterias in a ' cage,^ and left them until the 23rd, without giving 

 them any food ; 1 weighed them, noted their weight, then put 

 them again in the cage, and placed within their reach a quantity 

 of li\dng NaticcB of various dimensions, and some Trochi. The 

 Asterias feeds only upon these mollusks. 



The niode in which it swallows and arranges them in the 

 interior of its rays and body is very curious. It commences by 

 seizing a small Natica wnth the point of each of its rays, and 

 then brings it gradually up to the bod}^, which is of a spherical 

 form ; it places on, or beneath the body a circular row, and then 



