6 American Quarterly Microscopical Journal. 



Lying along, and partly in the cleft of the sheath, are a pair 

 of tubular darts or lancets, having a fine cutting edge curved 

 to the inward side, while the lateral margins are serrated near 

 the point with ten deep retrorse barbs. These lancets are cap- 

 able of being projected beyond the sheath, so as to increase 

 the depth of the wound made by that instrument. 



A sac or reservoir is connected with the base of the sheath 

 and discharges into it by the rapid contractions of its muscular 

 coats, a poisonous fluid which is conducted into the wound 

 through a channel between the concave faces of the lancets ; 

 the escape of this fluid between the outer (inferior) convex 

 edges being prevented by a valve, consisting of a thin flange 

 projecting inward from each. 



A mechanism resembling the hydraulic ram is found in the 

 cylindrical part of the sheath, which serves to inject the poison 

 with great force through several small apertures, near the 

 points of the tubular lancets, into the extreme limit of the 

 wound to which they are projected. 



The sheath and lancets are protruded, not by the direct 

 action of the muscles, but in order to impart great penetrating 

 force to the former, and a quick motion to the latter, they 

 are actuated through a peculiar combination of levers, which 

 is perhaps the most curious and interesting feature of the en- 

 tire mechanism. 



Finally, a pair of palpi, or feelers, are uniformly projected, 

 in advance of a thrust made by the sting, to determine the 

 most vulnerable point of attack. 



This being the general plan of this apparatus, the details of 

 its structure, and the particular function of each part, will be 

 better understood by a reference to the drawings and dia- 

 grams, which are exact delineations of the objects presented, 

 and very correct as regards the relative proportion of con- 

 nected parts, though the different figures are not drawn to the 

 same scale of amplification. 



Fig. I presents a view as seen from the inferior side of all 

 the pieces connected with the " terminal armor" of the Honey 

 Bee, with the exception of the poison gland, only the excretory 

 duct of which, P, is here seen. 



The median, or more darkly shaded .piece A, extending the 

 entire length of the figure, and loosely enclosed by the vulva. 



