folsom: mouth-parts of orchesella cincta. 27 



lateral surfaces of the glossa are strongly concave (Plate 4, Fig. 29), and 

 receive the maxillae, which lie adjacent to it. The maxillae normally 

 approach each other in the space left free between the upper surface of 

 the end of the glossa and the under surfaces of the paraglossae (Plate 1, 

 Fig. 3). The glossa is prolonged behind into a pair of slender, diverg- 

 ing, chitinous stalks or legs, by von Stummer-Traunfels termed the 

 "Stiitzgerust " (Figs. 10, 22, 23, pdJ). The enlarged base of each bears 

 some resemblance to a human foot (pd.). The toe of the foot, which 

 underlies the cardo of the maxilla, is attenuated into a long ligament 

 which bends around the base of the cardo and attaches itself upon the 

 outside of the base of the stipes (Fig. 10, Eg.). The dorsal edge of the 

 stalk is extended and modified to form a second ligament (%.'), which, 

 as previously stated, unites with a ligament from the toe of the cardo, a 

 suture remaining to indicate where the two ligaments united. 



The glossa is lined with a layer of well developed pigmented epi- 

 thelium, containing large oval nuclei (Plate 1, Fig. 3). A central 

 tubular cavity is left, however, which is a branch of the general body 

 cavity. The possible glandular nature of the tongue will be discussed 

 later. 



Labium. 



The labium, or lower lip (Plate 3, Fig. 24), is a single plate, formed 

 by the union of two lateral plates, as indicated by a conspicuous median 

 suture. Either half of the labium is divided by sutures into three dis- 

 tinct regions. The anterior region (j'^p.) bears five prominent tubercles, 

 from the apex and sides of which project several subulate bristles. The 

 intermediate region (?nen.) is of lunate form, thickly chitinized along the 

 mesal margin, hinged along the posterior curving suture, and beai'S a 

 few setae. The posterior and most extensive region (sb'men.) is almost 

 divided into two sclerites by an oblique suture, which however becomes 

 obsolete at its posterior end. This third region is laterally fixed to the 

 clypeus, is posteriorly distinguished from the gula by a deep oblique 

 suture, and bears a number of setae, many of which are barbellate. 

 The halves of the labium are firmly fused together, except anteriorly, 

 and are not easily separable ; but the fusion involves only the ventral 

 margins of the mesal faces of both plates, in such a way that a trough 

 or gutter is left within the buccal cavity (Fig. 25, and Plate 4, Figs. 28, 

 29, sid.). At the posterior end of the median longitudinal suture begins 

 the linea ventralis of Tullberg (Fig. 24, In. v.), an external median 

 ventral gutter formed by two thin longitudinal ridges of chitinous cu- 



