22 



At about three o'clock, the company arrived, by special invita- 

 tion, at the beautiful mansion of Mr. Bouvc, where, after exam- 

 ining his magnificent mineralogical and geological cabinet, the 

 Society sat down to a handsome banquet provided by him. 

 After dinner, and a song from the accomplished Curator of 

 Botany, a portion of the party scattered themselves for the col- 

 lection of specimens, whilst the remainder assembled under the 

 trees to listen to some remarks upon what had been seen during 

 the morning. 



Some observations were made by the President, upon the man- 

 ner in which the Limidus (the Horseshoe Crab) casts its shell. 

 Unlike that of the crabs and lobsters, this is cast entire. The 

 first step towards the formation of a new shell, is the separation 

 of the soft parts from the old integument ; the new covering, at 

 first quite soft, is everywhere minutely convoluted, in order to 

 accommodate its increased surface. The old shell splits around 

 the convex border of the head and thorax, and the Limidus 

 escapes, withdrawing its legs, gills, and tail. The animal imme- 

 diately expands, the convolutions of the new shell are drawn out, 

 it hardens, and the growth is finished until the period of the next 

 moulting. Dr. Wyman had found the horseshoe in the stage 

 preliminary to shedding the skin, and in the act of leaving it ; in 

 the latter case, the animal was not yet freed from the old shell, 

 but its growth was already complete. From observations made 

 on many shells, he had ascertained that at each moulting the 

 increment was by one third to one half of the dimensions of the 

 animal. Growth takes place at no other time than during the 

 moulting period. The cuticle which lines the oesophagus and 

 stomach is withdrawn at the time the external shell is cast, and 

 comes away in connection with it. 



Mr. Francis Alger spoke of the great Beryl formation in the 

 town of Grafton, New Hampshire, describing its crystals of 

 gigantic dimensions which had been discovered there. One of 

 these crystals, which he had caused to be removed and conveyed 

 to Boston, weighed nearly 2^ tons, and was five feet in length. 

 Another, the largest single crystal in the world, as far as is 

 known, is nine feet in length, being a six-sided prism, the 

 several faces of which measure respectively in width through 

 the greatest diameter of the crystal, 2 feet 8 inches, 2 feet, 1 



