112 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



such as are showu in Plate 7, Figures 46-50, which successively repre- 

 sent sections in moi'e posterior planes. 



Figure 46 shows the right maxilla {mx.^) sectioned in front of its basal 

 opening and lying free in its pharyngeal pocket ; it also shows the stout, 

 supei'ficial chitiuous stalk {j^dJ) in its hypodermal groove. Figure 47 

 represents the beginning of an evagiuation (pli.) of the dorsal wall of 

 the pocket, which grows down between the maxilla and chitinous stalk. 

 Passing back, the intruding hypodermal fold expands, as in Figures 48 

 and 49 {pli.), until it almost encloses the stalk. Finally, in the region 

 of the maxillary aperture (Figure 50), and on account of its obliquity, 

 adductor muscles (mn.) ave enabled to pass directly from the inner wall 

 of the stipes to the chitinous stalk (pd/). They are not attached di- 

 rectly to the stalk, but to an intervening cuticula (da.) ; this, however, 

 amounts to the same thing, because the cuticula and stalk become fused 

 together at about Stage 7, and hardened into a single piece. It should 

 be stated that the hypodermal cells which formed the intervening 

 cuticula, as well as those which formed the stipes, are seen in eni- 

 bryological life only ; they disappear at the origin and insertion of 

 muscles. 



At Stage 7 the end of each stalk is already feebly fused with the end 

 of the cardo to form an articulation (compare Plate 4, Figure 25, with 

 Plate 6, Figure 38, ate). This is a simple process, as both cardo and 

 stipes are superficial and contiguous structures. In the adult Orchesella 

 (Folsom, '99, Plate 2, Figure 10, lt[/.') a long ligament unites them, and 

 I mentioned a distinct suture as possibly indicating the end-to-end union 

 of two ligaments, which doubtless occurred. 



The lingual stalks, then, are quite independent of the lingua in origin, 

 except that they are thickened cuticular structures continuous with the 

 lateral cuticula (Plate 7, Figure 45, cht.) of the lingua. When dissect- 

 ing out the lingua at Stage 7, it frequently breaks away from the stalks 

 at the sutures (snt.) shown in Plato 4, Figure 25 ; these sutures later 

 become obliterated, however. 



The lingual stalks of Collembola have been mentioned by several 

 nnthors, for example, de Olfers ('62, p. 18) in several genera, Tulll)erg 

 ('72, Taf. IV., Figur 17) in Tomocerus, and v. Stummer-Traunfels 

 ('91, Taf. I. Figur 7) in Tetrodontophora. I have seen them myself 

 in all the more common genera ; they undergo but little modification 

 within the order. 



As to the development of the lingua and superlingntc in other insects, 

 very little has been written. Packard ('71, p. 17), as quoted on page 



