NATURAL SCIENCES OF PHILADELPHIA. 205 



The size of the animalcule is about tlicl-5th of a line ia diameter. It appears 

 to be permanently lixcJ to the positions in wliicli it is found. When disturbed, 

 it folds up its oral cup like an umbrella and retracts it within tlie body. By 

 means of it, it catches its prey, which consists of smaller animalcules. From 

 the stomach of one individual I squeezed out as many as fifty of the latter. 



For the genus and species the name Dictyophora vorax is proposed. 



December loth, 1857. 

 Vice-President Bridges in the Chair. 



A paper was presented for publication in the Proceedings, entitled 

 " Prodromus Descriptionis Animaliuiu Invertebratoruui quae in Ex- 

 peditione ad Oceanuni Pacificum Septentrioualem aRepublica Federata 

 missa, Cadwalladcro Ringgold et Johanne Rodgers ducibus, observavit 

 et descripsit W. Stimpsou, Pars Tcrtia," which was referred to a Com- 

 mittee. 



Mr. Lea exhibited the plates accompauyiug his paper, recently pre- 

 sented to the Acadfciuy, on fresh water Naiades collected in Siam, &c., 

 by Dr. House, at the suggestion of Mr. ILiines and others of New York. 

 Seven! of the specimens are very similar to our own species from the 

 valley of the Ohio. A specimen from Australia much resembles the 

 U, Ilopetoneusis, Lea, from Southern Georgia. 



December 22d, 1857. 

 Vice President Bridges in the Chair. 



A paper was presented for publication in the Proceedings, entitled 

 " Observations on a Group of Fossil Shells found in Tippah Co., Miss., 

 with descriptions of fifty-five new species," by T. A. Conrad, which 

 was referred to a Committee. 



Mr. Lea stated, in presenting a specimen to the Academy, that he had visited 

 the locality at Braintree, 10 miles south of Boston, where specimens of large 

 Trilohites have been recently found. The attention of Prof. W. B. Rogers was 

 called, some fifteen months since, to "this unique and most interesting locality,'' 

 by Peter Wainwright, Esq., residing in the neighborhood. Mr. Lea agreed en- 

 tirsly with Prof. Rogers in placing this formation among the more ancient of 

 the Paleozoic jteriods. It lies directly on the granite rocks, or rather it is 

 squeezed in and is embraced by these rocks, (on the east and west sides,) which 

 are disturbed by an upheaval. The formation here is about three hundred 

 yards wide, and lies in a south-east direction. In examination of the quarry, 

 Mr. Lea was kindly assisted by the owner, Mr. E. Hayward, who now carefully 

 preserves the best specimens which are brought to light. He pointed out to 

 Mr. Lea the parts of the quarry where most of the specimens were found, and 

 where some impressions were still remaining in place on the surfaces of the 

 stratification. These surfaces dipped to the south 68°. The rock consists of 

 a very hard, gray, slaty sandstone, frequently breaking into irregular cross 

 fractures. The Trilobitcio\in& here is of great interest. It belongs to the genus 

 Paradozides, and is no doubt the same as described by Prof. Green many years 

 since, under the name of P. IJarlani, of which there is a cast in the collection of 

 the Academy, and which, on comparison with the specimen now presented, 

 proves to be undoubtedly identical. Barande describes and figures several 

 species of the genus Paradoxides from the lower Silurian of Bohemia, which are 

 closely allied to this, and prove conclusively that the strata must be nearly if 

 not precisely on the same horizon. 

 1857.] 



