1885.] NATURAL SCIENCES OP PHILADELPHIA. 1 1 '.» 



the second spring and summer, till then hidden between the bases 

 of the surrounding tubercles, and for the greater part buried in 

 the tissues of the plant; in spring the young fruit suddenly (in 

 one or two weeks) grows to its full size, 9-12 or even 15 lines 

 long, protruding far above the tubercles, and forming an interior 

 (exterior?) scarlet circle, around the inner circle of rose-colored 

 flowers." He did not perceive that the development of the fruit 

 was not a growth, but the emergence and stretching out of struc- 

 ture the actual growth of which had already been matured ; that 

 it was an elastic and not a growing fruit. 



May 5. 



Mr. John H. Redfield in the chair. 



Twenty-one persons present. 



The following papers were presented for publication : — 



" On the Air-bladder of Fishes," by Charles Morris. 



"A Review of the Genus Phrynosoina," by Alan F. Gentry. 



Spawning of Fidgur perversus. — Mr. Jos. Willcox remarked 

 that during the month of March, 1884, and recently, during the 

 past March, in Clearwater Harbor and Sarasota Bay, in Florida, 

 he observed many egg-cases (more than a hundred) of Fulgur 

 perversa S, both recently completed and during the process of 

 their formation. 



When completed, one end of the string of egg-cases floats freely 

 in the water, while the small end is fastened to a shell under the 

 sand. Being thus anchored it is not liable to be removed from 

 its original position 113- the force of the tide. Whenever both 

 ends of the egg-case are found to be under the sand, the middle 

 portion being above the surface in the form of a loop, the parent 

 conch will always be attached to one of the ends, but invisible to 

 the beholder. All the processes connected 'with the subject of 

 the reproduction of this species are performed under the sand, 

 until the egg-cases are completed. When about to spawn, a place 

 is selected where the sand is not packed hard. At that time 

 a disposition is manifested to assemble in communities, usually 

 upon a sand-flat where the water is never deep, and where the 

 receding tide leaves the egg-cases dry and exposed to the warm 

 rays of the sun during a portion of each day. Many egg cases 

 however, are to be seen, which are always submerged. In such 

 instances the eggs may require a longer time for their develop- 

 ment. Although, during the early part of April, many egg-cases 

 were observed that were completed, in no instance were the 

 young shells found to be developed in them. 



When the mollusk is about to spawn, it first descends into the 

 sand deeply, and attaches the egg-case to a bivalve shell. As the 



