452 CALIFORNIA ACADEMY OF SCIENCES. 



tend slightly around the outer margins of the sclerite. 

 Each is an oval structure, having the long diameter ex- 

 tending from within outwards and backwards. The ven- 

 tral surface is convex, and the dorsal surface concave, 

 while the whole is very much flattened dorsoventrally. 

 Each is invested in a thin chitinous envelope, and is seated 

 upon the ventral anterior surface of a chitinous pedicle 

 which is expanded where it receives the gland. The ex- 

 panded portion of the pedicle is thin and convex ven- 

 trally, so as to fit the dorsal concavity of the gland; and 

 the middle of its shallow dorsal concavity lies below and 

 external to the outer edge of the sclerite. Back of the 

 glands the pedicle extends backward and outward, but 

 not so much in the latter direction as the long axis of 

 the gland, so that the two form an obtuse angle inwardly. 

 The part of the pedicle not having the gland attached is 

 about as long as the other part, and it is somewhat more 

 chitinous. It tapers backward, but ends in a foot- 

 shaped expansion, with the toe turned outward. To this 

 is attached a large, wide muscle which extends back- 

 ward to its origin in the posterior part of the head cavity. 

 At the posterior end of the gland, on the ventral surface, 

 a duct arises which passes forward, attached closely to 

 the gland, to its anterior end; here it leaves the gland and 

 continues forward, but soon turns inwardly and dorsally, 

 and then posteriorly, meeting and fusing with the duct 

 from the gland of the other side. This common duct 

 then runs backward to the sclerite, which it enters as al- 

 ready described. The relative positions of the glands 

 and sclerite vary somewhat, since they are evidently 

 movable structures, judging from the attached muscles, 

 and hence, also, the duct varies in position; but all such 

 changes are slight. The free portion of the duct con- 

 sists of an inner chitinous tube continuous with that 



