266 
ORIGINAL COMMUNICATIONS. 
Fig. 1, in the Plate, represents the dorsal view. Fig. 2, 
the ventral. 
The history of this insect is the following. — A small quan- 
tity of them was sent from Valparaiso by Dr. Styles of that 
place to Dr. Ruschenberger of the U. S. Navy; he stated in 
the letter which accompanied them, that he had procured the 
insect from an apothecary of his town, who assured him that 
it was peculiar to Chili, and extensively used by the native 
practitioners to produce vesication ; it was also asserted that this 
effect was fully accomplished in four hours, and that it was 
attended with more uneasiness than by the common Spanish 
fly. From some trials which have been made, vesication 
was fully accomplished at the termination of six hours, which 
is less by one half than the period usually allowed to the offi- 
cinal article; but perhaps some portion of activity had been 
lost from age, as the specimen experimented upon had been 
kept nearly three years. 
ART. XLIV.— NOTES ON THE SPECIES OF CASSIA WHICH 
YIELD THE SENNA. By Joseph Carson, M. D. 
(Continued from the last.) 
In continuation of the remarks which were made in the 
last number, we shall now take up the consideration of such 
plants as enter into the composition of the Alexandrian Senna, 
and form component portions of that drug, but which are se- 
parate and distinct in botanical affinities from the genus Cassia. 
From the circumstance of their being either accidentally or 
designedly associated with it in commerce, all points of their 
history become matters of interest. It has been the design 
throughout, to present our statements in a way calculated to 
exhibit the degree* of certainty which had been attained with 
regard to the species of Cassia already noticed. An appre- 
ciation of the difficulties to be encountered in the attempt to 
arrive at just conclusions, could only be entertained, by con- 
trasting the accounts and descriptions of the authors who have 
