jan. — mar. 1857.] voyage from England to Madras. 151 



vivid green, but when the animal died it quickly faded. Some au- 

 thors affirm that each of the tubercles with which their surface is 

 studded, constitutes a distinct animal ; but while admitting its com- 

 pound nature I should feel rather disposed to compare these tu- 

 bercles or gemmules to the buds on a tree ; in short I consider it 

 as one of these remarkable instances where the animal kingdom 

 closely approximates to the vegetable, and is in some measure 

 regulated by the same laws. In their native element they diffuse 

 a strong phosphorescent light for a distance of several inches from 

 their bodies, and their aggregate numbers so illumined the stem of 

 • the ship, that moderately large print could be read at midnight. 



As we neared the equator a succession of calms temporarily put 

 a stop to our towing experiments, the ship making no perceptible 

 way through the water. 



April the 29th in Lat. 22-1 S. Long. 387 W. After so many 

 fruitless attempts we were gratified to-night by taking in the net 

 three different species of Hyalcea and two specimens of another 

 genus " Cuvieria" Fig. 26, the flat Hyalcea Fig. 12, was first 

 caught about twilight, the other, Figs. 13 and 14, were taken after 

 dark until 8 p. m. when the wind became too high. 



Both of these genera belong to the Pteropoda, a class the 

 position of which has much distracted the opinions of naturalists, 

 some assigning them a rank second only to the 1st class or 

 Cephalopoda, while others have variously considered them 

 superior or inferior to the Gasteropoda, or degraded them 

 below the level of the Acephalous bivalve. Pteropods being 

 provided with fins can traverse the ocean, a faculty they possess 

 in common with Cephalopods, and in this particular they might 

 be considered superior to the creeping Gasteropod, but when we 

 compare their interval conformation, habits and instincts, the Gas- 

 teropod is seen .to exhibit proofs of a much higher state of deve- 

 lopment than the Pteropod, which being destitute of feet or pre- 

 hensile organs, cannot creep or attach itself to floating objects. 

 Nor is the power of swimming " per se" an indication of high 

 organization, it is in fact possessed by some of the Gasteropods 



