I08 RESEARCHES IN HELMINTHOLOGY AND PARASITOLOGY. 



In Structure the sponge is composed of an intertexture of granular 

 matter and pin-like silicious spiculse. Several species of Cliona are 

 indicated by European naturalists, but are not characterized with 

 sufficient detail to determine whether the one above indicated is 

 distinct or not from them. 



Dr. Iv. further adds, it might appear only of scientific interest to 

 observe a structure so low as the sponge is classified in the organic 

 kingdom, endowed with the power of penetrating such dense and 

 hard bodies as the shell of the clam and oyster, but he suspected 

 that the agency of the boring sponge was a highly important one 

 in the sequence of natural phenomena, as it is a means by which 

 dead shells are rapidly decomposed to be dissolved in the ocean 

 water, where they may again serve as the elements of construction 

 of the habitations of the rising generations of molluscous animals. 

 In confirmation of this view Dr. L. stated that an extensive bed of 

 oysters, which had been planted by Mr. Thomas Beasley, at Great 

 Egg Harbor, and which was in excellent condition three years since, 

 had been subsequently destroyed by an accumulation of mud. The 

 shells of the dead oysters, which were of large size and in great 

 number, in the course of two years have been so completely riddled 

 by the boring Cliona that they may be crushed with the utmost 

 ease, whereas without the agency of this sponge the dead shells 

 might have remained in their soft muddy bed, devoid of sand and 

 pebbles, undecomposed perhaps even for a century. 



[February, 1857. No. 178. See Bibliography.] 



Dr. Leidy made the following observations on entozoa found in 

 the Naiades. 



He had observed a curious parasite allied to Aspidogaster coiic/ii- 

 cola, \\\iQsX\w<g Aiwdonta /hcviati/is and A //odonhr lacjistris, within the 

 cleft of the upper branchial cavity, adhering to the outer surface of 

 the renal organ and the contiguous margin of the foot. The new 

 parasite, for which the name of Cotylaspis insignis was proposed, is 

 from ^ a line to i line long, curved funnel-shaped, wath the base 

 forming an oval ventral disk provided with an outer circle and an 

 inner row of acetabula 29 in number. The animal is provided with 

 distinct eyes, while Aspidogaster, in accordance with its being im- 

 prisoned in the pericardium of the Naiades, is blind. 



[December, 1857. No. 183. See Bibliography.] 



Dr. Leidy called the attention of the members to a bottle contain- 

 ing numerous specimens of a large species of Gordius discovered by 



