318 [Dec, 1S45. 



tarsi dull testaceous. There are doubtless specimens of this species which have 

 the thorax rufous. 



Pelecotoma, Fisch. 



P. flavipes. Black : antennae, palpi and feet, yellowish. 2£ 1. long. Caro- 

 lina. 



Slender, subcylindric, subparallel, Hack, pubescent: antennae brownish, with 

 the basal joints testaceous ; palpi testaceous : thorax strongly conic : indented 

 each side of the middle at base : elytra entire, minutely shagreened like the 

 thorax and head : beneath blackish : feet testaceous. yellow : nails very small. 



(To be continued.) 



The following report, the conclusion of which was read at 

 the meeting of 23d inst; was referred for publication to the 

 Committee on Proceedings. 



Examination and analyses of samples of the alluvial soil of the Nile, from 

 Korosco, in Nubia. 

 By Walter R. Johnson. 



The specimens about to be described are the same which were on the 21st 

 of January last presented to the Academy, by Mr. Gliddon, from Dr. Richard 

 Lepsius of Berlin, then in Egypt, (see proceedings of the Acad. vol. 2, p. 

 195,) and referred to the reporter for examination. 



No. I. — Earth of the Nile taken from the summit of hillocks at thirty feet 

 above the present level of the river about a mile above Korosko. 



This earth is partly in powder and partly in lumps. In some of the latter, 

 distant traces of folia, or plies, marking an imperfect stratification, are to be 

 seen. Along these seams fractures often occur. Throughout the lumps are 

 to be observed innumerable cavities or spiracles of a tortuous form, giving 

 the impression of having been produced by some species of vermes. Many 

 of these are lined and some nearly filled up with carbonate of lime. 

 Tubes of the same material are found in a separate state, and some plane sur- 

 faces are covered with it. The whole has a light spongy appearance, and, 

 the resemblance is strengthened by the vermicular cavities, which remind 

 one of the white tubes often found traversing masses of common sponge. 

 Very fine micaceous particles are distributed pretty copiously through the 

 masses, distinctly perceptible to the eye, and clearly exhibiting their forms 

 under the lens. To the naked eye no ferruginous appearance is discernible, 

 but the microscope shows innumerable points of a deep red colour. The mud 

 appears to have been deposited at successive, but not very distant periods ; 



