26 



arranged that they form twenty-four long and flexible arms bear- 

 ing spines or bristles, adapted for securing prey. They are 

 thrown out and drawn in with great rapidity, like a many- 

 fingered hand, and catch any suitable food that comes within 

 range. (A large number of living specimens were on view, 

 incessantly at work in the way described). The muscles 

 regulating these movements are connected with a nervous system 

 described by Darwin, as showing equal development with a 

 decapod crustacean. 



The living specimens of the larva of the Balanus have the 

 appearance of an entomostracous crustacean. The oval body is 

 covered by a dorsal shield ; it is furnished with a single eye, and 

 has three pairs of swimming legs. After the first moults, 

 antennas are developed. In the second stage the body is en- 

 closed in a bivalve shell, the antennse are aborted, and two fleshy 

 projections appear which, in the next stage, develop into pre- 

 hensile antennae. In the third or pupal stage, the single eye has 

 divided into two distinct eyes, and instead of three pairs of legs 

 there are six. 



In the last stage the mouth is but rudimentary, so that the 

 larva cannot eat, and as soon as it has found a suitable substance 

 it attaches itself by its antennse, which have sucking disks, and 

 undergoes its final change. (Mr. Saunders exhibited a wine 

 bottle to which about two dozen full grown animals had attached 

 themselves. It was found floating, being corked, and showed 

 that the barnacle can adhere to the smoothest surface.) Darwin 

 had traced, in the middle of the disk, cement ducts by means 

 of which the creature can fasten itself to any substance. These 

 ducts continue during the life of the animal to convey cement 

 to the point of attachment. The shells of the pupa, eyes, &c. 

 are moulted, and six pairs of cirri are formed, as well as the 

 valves or capitulum of the mature barnacle. 



In the case of the sessile acorn-shells, that portion of the 

 head by which the animal becomes attached e.xpands into a 

 broad basis of calcareous matter. The valves are placed M'ithin 

 a conical shell, and move up and down, opening for the protru- 

 sion of the cirri. 



Mr. Saunders showed a variety of specimens, living and dead, 

 to illustrate that the barnacle will attach itself to almost any 

 substance. He doubted if the difficulty as regards ships' bottoms 

 could be overcome. 



JUNE. 



Br. E. M. Boclcly, of Ranvsgcvte, on Salt, and the 



position it Jiolcls in Geology. 

 Abstract salt, or chloride of sodium, is found in six different 

 physical conditions but there are only three feasible explanations 



