22 OCEAN LIFE. 



saucer* The shell fixed within the stomach was so placed as to 

 divide it completely into two halves, so that the body stretched 

 tensely over, had become thin and flattened like a pancake. All 

 commnnication between the inferior portion of the stomach and 

 the mouth was of course prevented, yet instead of emaciating 

 and dying of an atrophy, the animal had availed itself of what 

 had undoubtedly been a very untoward accident, to increase its 

 enjoyments and its chance of double fare.' A new mouth fur- 

 nished with two rows of numerous tentacula was opened up on 

 what had been the base and led to the under stomach. The in- 

 dividual had indeed become a sort of Siamese twins, but with 

 greater intimacy and extent in its unions." 



Metridium Prsetextum, (J. P. Couthony,) exhibited wholly in 

 the plate, is generally found with its body covered with sand, 

 having its disc expanded on a level with the surface. When mo- 

 lested they entirely conceal themselves beneath the sand. Spe- 

 cimens were obtained off Santa Cruz : also on the north side of 

 the harbor, near Praya Grande. Another allied species was 

 observed by Dr. C. Pickering in the sand among the rocks out- 

 side of the harbor. 



ACALEPHJE. 



"TN the third division of Acalephse, denominated by Cuvier, 

 * Acalephes Hydrostatiques,' the body is supported in the water 

 by a very peculiar organ, or set of organs, provided for the pur- 

 pose. This consists of one or more bladders, capable of being 

 filled with air at the will of the*animal, which are appended to 

 the body in various positions, so as to form floats of sufficient 

 buoyancy to sustain the creature upon the surface of the sea, 

 when in a state of distension ; but, when partially empty, allow- 

 ing it to sink, and thus escape the approach of danger." " The 

 most conspicuous, if not the most typical, member of the Physo- 

 grade order of Acalephae is the Physalia, (known to sailors by 

 the name of the Portuguese man-of-war,) in w r hich all that part 

 answering to the disc in the ' Pulmograde' order, is expanded 

 into a bag, the major part of which is occupied by an air-bladder, 

 whilst the digestive cavity is subdivided amongst a series of ap- 

 pendages attached to one part of the under surface of the bag. 



