INSECT VARIETY. 237 



VI.;, Fig-. 1, c) is central on the disc, small and triangular; the 

 other, situated near the anterior edge, consists in two dissimilar 

 thin limbs [h), concave inwardly, that meet it in an obtuse angle, 

 the upper being the shorter ; and in a third darker and thicker 

 tongue-shaped process [h') from their point of intersection, 

 convex anteriorly and concave posteriorly, which Von Siebold 

 compares with the cochlea. On account of its three parts, it has 

 been proposed to call this the composite piece. 



The Miillerian ganglion emits two processes. The shorter 

 is inserted at the upper extremity of the composite piece ; the 

 other, longer and thinner, proceeds in a gentle curve to the 

 central triangular callosity, and, according to Von Siebold, it also 

 sends a broad band to the edge of the drumskin posterior to the 

 spiracle. Beneath the microscope, the Miillerian ganglion 

 appears to be really a bladder filled with a watery fluid, which, 

 if pricked Avith a needle, immediately collapses, nor can it be 

 isolated from the horny pieces without injury. The nerve pene- 

 trating it swells internally into a true cylindrical and proportion- 

 ately large ganglion as it nears the tongue-shaped process, where 

 the bladder above, covered with white pig-ment, presents a limpid 

 termination. In this terminal translucent portion (Plate VI., 

 Fig. 2) , Von Siebold was enabled to distinguish little stalked bodies, 

 presumably the enlarged terminations of the nervous threads (m) ; 

 nucleated cellular bodies (Z) also characterise either part. 



Leydig, Hensen, and Oscar Schmidt, on the Continent, have 

 subsequently directed their attention to the minuter structure of 

 the horny pieces submitted to high microscopic powers, and 

 to their attachment to the Miillerian ganglion. Leydig de- 

 scribes the central triangular horny piece as hollow and pene- 

 trated by numerous pores that confer on it a striated appearance ; 

 and Herr Schmidt finds nerves radiating hence over the surface 

 of the drumskin in a fine membrane, that probably serve to 

 conduct the sonorous vibrations. The process of the Miillerian 

 ganglion proceeding to this capsular piece, Herr Schmidt alleges 

 in some species, after forming a small ganglion, j)enetrates the 

 membrane of the drumskin previously to its junction. These 

 authorities notice the attenuation of the drumskin posteriorly, 

 its concentrically striated appearance as the mesh of black or 

 reddish cellular and pear-shaped bodies which covers the anterior 



