34 Journal New York Entomological Society. [Vol. xx. 



narrowly oval in shape. It opens into a shallow pit (Fig. 9) bordered 

 by tubercles giving rise to hairs. These hairs (Fig. 7, h) are beset 

 with rather long spicules, except basally, and probably serve to hold 

 the drop of liquid in place after it has been exuded. As is shown in 

 Fig. 8, h, when the sac is thrust out, their position is outside. In the 

 center of the pit is a small, transverse opening through which the 

 liquid is voided. Directly below this opening is a sac (Figs. 6 and 

 7, /), a simple invagination of the cuticula and of the hypodermis. This 

 fact is shown in Fig. 8. It is this sac which appears as a papilla when 

 the liquid is voided (Fig. 2, p), being everted by blood-pressure and 

 retracted by two retractor muscles (Figs. 6 and 7, r.m) , one attached 

 to each side of the sac. The other ends of these muscles are attached 

 to the body wall ventro-laterally. There are four glands supplying 

 the liquid (Figs. 9 and 10). These are irregularly rounded, the 

 anterior pair being the largest. Each is connected with the sac by 

 means of a short duct. Sections (Figs. 6, 7 and 8) show how these 

 glands open into the lumen (/) of the sac. The walls of the glands 

 consist of hypodermal cells with their basement membrane {b.m), 

 and are lined with a cuticular intima {int) traversed by pore canals 

 for the passage of the secretion from the cells to the lumen. The 

 cells lining the ducts appear to be much thicker than those of the 

 glands, and rounded within. The intima is also somewhat more 

 thickened here. The whole organ is very much like the organs 

 possessed by various caterpillars of the Lepidopterous families 

 Notodontidcc and Liparidcc, as described by Klemensiewicz (2). In 

 these, however, the secretion is used in defense. 



The evaginable organs are found on the eleventh body segment, 

 each being posterior to the spiracle of the same side and nearer the 

 lateral margin (Fig. i, e.t). When these are retracted there ia 

 visible only a round or oval spot. When thrust out (Fig. 2, e.t), they 

 have the appearance of whitish cylinders, bluntly rounded at the tips, 

 and crowned with long, slender setae (Fig. 4) arising from small 

 tubercles. These set?e are studded with fang-like projections from 

 the base to the tip. The organs are invaginations of the cuticula 

 and of the hypodermis. Fig. 3, drawn from longitudinal sections of 

 the retracted organ, shows the structure. Here, a thin layer of cutic- 

 ula {cut) forms a lining to the retracted diverticulum. In live speci- 

 mens the mouth of this is closed by folds of the cuticula. At the 



