90 



[June, 



Dr. Leidy next called attention to several fossils indicating new species of 

 extinct mammalia. 



The first was the crown of a molar tooth discovered by Captain Bowman, 

 U. S. A., in the sands of Ashley river, S. C. It most resembles the left lower 

 penultimate molar of the bear, but the triturating surface is more generally 

 level, and presents less disposition to the formation of cusps. The specimen 

 measures 24 m.m. antero-posteriorly, and 17 m.m. transversely. For the genus 

 and species supposed to be indicated by the specimen the name of Aretodus pris- 

 tinus was proposed. 



The other fossils consisted of two specimens loaned by Prof. Hall, of Albany, 

 and constitute part of the collection made by Messrs. Meek and Hayden, during 

 an expedition to Nebraska Territory in the summer of 1853. They were found 

 on Bijou Hill, east of the Missouri River, in a tertiary formation surmounting 

 cretaceous beds. 



One of the specimens is an inferior molar of a solipedal animal, apparently 

 intermediate to Equus and Anchitherium, the enamel folding upon the triturating 

 surface being less complex than in the former, and greater than in the latter. 

 It appears to have had an envelope of crusta petrosa as in the horse, though 

 nearly all removed in the specimen. In size it is relatively long compared to 

 the corresponding teeth of A7ichitherium i but is short compared to those of 

 Equus. Its antero-posterior measurement in 17 m.m. For the genus and species 

 the name of Hippodon speciosus was proposed. 



The remaining specimen is the fragment of a lower jaw, containing a last pre- 

 molar and the first true molar of a small ruminant allied to the Musks. The 

 last premolar on the triturating surface presents a series of five folds projecting 

 inwardly. Its measurement antero-posteriorly is 8 m.m. The inner side of the 

 true molar is nearly as plain as in those of Pceb rot her item. Its measurement 

 antero-posteriorly is also 8 m.m. For the genus and species the name of Mery- 

 codus necatus was proposed. 



9 



June ISth. 

 Dr. Ruschenberger in the Chair. 



A letter was read from Dr. W. P. Gibbons, dated San Francisco, May 

 16, 1854, transmitting the specimens of viviparous fishes acknowledged 

 this evening; also a paper intended for publication in the Proceed- 

 ings, entitled, u Descriptions of four new species of Viviparous Fishes 

 from Sacramento River and the Bay of San Francisco. Read before 

 the California Academy of Natural Sciences, May 15th, 1854 ; by Wm. 

 P. Gibbons, M. D." 



Referred to Dr. Le Conte, Dr. Leidy, and Dr. Hallowell. 



Dr. Hallowell presented a paper for publication in the Proceedings, 

 entitled, " Remarks on the Geographical distribution of Reptiles, 

 with descriptions of several species supposed to be new, and corrections 

 of former papers ;" which was referred to Dr. Leidy, Dr. Da Costa, and 

 Dr. Le Conte. 



Dr. Da Costa directed the attention of the Academy to a new process which 

 he had lately employed in making minute injections. In order to insure a greater 

 rotundity and distinctness of the vessels than is usually obtained, he performed 

 a series of experiments with solid substances dissolved in ether, and as evidence 

 of the results he submitted several specimens to the inspection of the members. 

 The substances selected on account of their ready solubility were the resins, and 

 of these the sandarach and the Damarra copal were found to answer best. One 

 ounce of the resin was dissolved in about three ounces, or if mucous membranes 

 were to be injected, in about four ounces of ether. This was then filtered, and 

 enough finely ground yellow or red paint added to give to the injecting mass the 



