6 [Feb. 



his attention to the remarkable fact, that they are flattened, like tape, and as seen 

 under a power of forty or fifty diameters of Chevallier's microscope, each hair has 

 the precise appearance of an ordinary steel watch-spring. Dr. M. had repeated 

 the experiments of Dr. Meigs, with that gentleman's assistance, using one of 

 Oberhauser's microscopes, with the same result. Dr. M. also adverted to a 

 prominence at or near the top of the sacrum, which, so far as he could judge 

 from a very imperfect examination of it, as covered with the boy's usual dress, 

 seems to be a prolongation of the spinous and transverse processes over the 

 region in question ; and which would appear to be the osseous frame-work of 

 that fatty cushion which is of proverbial occurrence in the Hottentot women. Dr. 

 M. expressed a hope that he might yet be able to examine this structure more 

 carefully, and report the facts to the Society. The boy's head corresponds, in most 

 of its developments, to those of two Hottentot skulls in Dr. M.'s collection, sent 

 him by Mr. John Watson, of Cape Town. The mental and moral questions con- 

 nected with the history of this youth, possess an extreme interest, but can only 

 be correctly judged of after more extended inquiries. 



Mr. Ashmead made some remarks on what he considered a peculiarity in the 

 calcareous spar, from the Rossie Lead mines, in New York. 



The general form presented by fractured crystals of calcareous spar is 

 rhomboedrous. Cleavage is perfect parallel totheprimary planesof a rhomb, andis 

 therefore three-fold. 



Some time since, Avhile engaged in reducing to convenient size for the cabinet, 

 some specimens of double refracting spar from the above locality, he observed that 

 some of the fractured crystals were susceptible of mechanical division in different 

 directions from those of the planes of a rhomboedron ; this induced him to slice off 

 the laminae wherever he found cleavage was perfect, and by proceeding with this 

 sort of dissection, the result was a nucleus, of a perfectly geometrical form. It is 

 a solid, bounded by six isosceles triangular planes of similar lustre, or two obtuse 

 three-sided pyramids, placed base to base ; it has but one axis passing through 

 opposite solid angles; assuming the axis to be vertical, the base is an equilateral 

 triangle. As the faces are not parallel, but inclined to each other, it is suscepti- 

 ble of perfect cleavage in six directions. 



The solid angle of the apex is similar to the obtuse solid angle of the rhomb, 

 therefore, by truncating the alternate solid angles of the rhomb, this solid is 

 produced. 



On motion of Dr. Leldy, the Corresponding Secretary was requested 

 to make some further inquiry of Dr. Joel Y. Shelley, of Berks county, 

 respectinfz; the locality of certain fossils from his vicinity, and the 

 depth at which they were found by him. 



February Ibth, 1848. 

 Vice President Morton in the Chair. 



A letter was read from Dr. William Maxwell Wood, U. S. N., 

 dated Philadelphia, February 11th, 1848, acknowledging the receipt 

 of his notice of election as a Correspondent. 



A letter M^as read from the Secretary of the Linnean Society of 

 London, dated Soho Square, December 30th, 1847, acknowledging the 

 receipt of recent numbers of the Proceedings of the Academy. 



A supplement to a communication presented at the meeting of Feb- 

 ruary 1st, 1848, entitled "Descriptions of some new plants collected 

 by Mr. William Gambel in the Rocky Mountains and California, by 

 Thomas Nuttall, F. L. S.," was read and referred to the same Commit- 

 ■tee, viz., Dr. Bridges, Mr. Gambel, and Dr. Zantzinger. 



