264 [September, 



the Journal, was referred to Dr. Zanlzingcr, Dr. Leidy, and Prof. 

 Haldeman. 



Dr. Leidy presented a paper entitled " Conspectus Crustaceorum 

 quse in Orbis Terrarum circumnavigatione, Carolo Wilkes e Classe 

 ReipublicEe FcederatEe duce, lexit et descripsit J. D. Dana," intended 

 for publication in the Proceedings of the Academy. Referred to the 

 committee on a former paper on the same subject by Mr. Dana. 



A letter was read from the Imperial Society of Naturalists of Mos- 

 cow, dated 6th and 18th May, 1851, presenting the numbers of the 

 Bulletin of that Institution announced this evening. 



Dr. LeConte exhibited a series of tertiary fossils from San Diego, California ; 

 they bore the closest resemblance to species now living on that coast : the forma- 

 tion is of great extent along the coast, although very narrow. In passing from 

 San Diego to the Colorado river, he observed that these tertiary beds were soon 

 succeeded by various kinds of porphyry, and these by sienitic metamorphic rocks; 

 the upper beds of these exhibited a very curious arrrangement, being light co- 

 loured, with fusiform masses of darker sienite, all placed with their longitudinal 

 axes parallel. The sections of these masses were 5 18 inches long, and li to 

 3 inches thick; these metamorphic rocks became more granitic, and in some 

 places gneissoid in their character towards the central part of the Sierra. Near 

 "Valleido these micaceous strata were much contorted. The eastern range of the 

 Sierra at this point consists entirely of a very coarse conglomerate, containing 

 rounded masses from the above mentioned metamorphic rocks of immense size : 

 the cement is granitic gravel, with a very small amount of calcareous matter. 

 Dr. LeConte was inclined to consider this chain, which is near 5000 feet high, as 

 belonging to the cretaceous epoch ; it is flanked by a smdl deposit of unstratified 

 drift, which becomes stratified a few miles distant from the base of the moun- 

 tains. Underlying the drift is a tertiary formation containing small beds of sand- 

 stone and gypsum, precisely as at San Diego: only Ostrea were found in these 

 beds. In a small hill north of Cariso Creek, he had found limestone beds com- 

 posed almost entirely of Gnathodon, and farther in the desert the same shell was 

 found in strata of clay, lying almost vertically. The desert has two levels, the 

 lower being covered with alluvium, containing numerous Planorbis and Anodon, 

 with smaller freshwater species now inhabiting the Colorado; the upper level is 

 about .^0 to 70 feet above this alluvium, and consists of stratified matter usually 

 verv sandv, and belongs to the drift epoch. The range of sand hills is formed 

 from the lighter portions of this upper level near the edge. In the northern part 

 of the desert is a salt lake, on the edge of which is a solfatara with boiling water 

 and mud; some of the water issues in jets from small cones of inspissated mud, 

 which form over the circular pools. The water deposited large quantities of sal 

 ammoniac tinged with sulphur, and within a short distance from these pools are eight 

 small volcanic mounds of lava and pumice ; for many miles stranded pieces of 

 pumice are found on the alluvial level. 



Dr. LeConte also expressed his opinion that the Vancouver Island coal belong- 

 ed, like that found in Oregon, to the tertiary epoch; it was very fragile and light, 

 exhaled a peculiar odor which is characteristic of tertiary lignites. 



It existed in a single stratum (as he learned from persons who had visited the 



