folsom: moutii-parts of anurida maritima. Ill 



to correspond with the adjacent convex surfaces of the first maxillae, as 

 in the adult (Plate 7, Figures ii, 45, cht.), and each ventro-lateral edge 

 extends under the neighboring maxilla ; in addition, the apex of the 

 lingua becomes separated into two lateral lobes by a median sinus, and 

 the dorsal surface invaginates to form a median longitudinal groove 

 (Plate 7, Figure 42, sul.) ; this lobed condition, however, is quite 

 secondary in origin. 



The lingua is thickly chitinized, and the hypodermal cells persist in 

 the mature organ. The superlinguae, on the contrary, are but thinly 

 chitinized and at maturity contain no distinct hypodermis cells, except 

 hasally, although a complete layer of cells exists in Stage 8. In this 

 stage (8) the superlinguse become triangular in cross-section, as in tlie 

 adult (Plate 7, Figure 44). Partly on account of the divergence of 

 the superlingufe in front, but principally owing to the convergence of 

 the mandibles and maxillte, the attenuated distal part of each superlingua 

 becomes situated between the apices of the mandible and the first 

 maxilla of the same side (Figure 44), and the superliuguse conform to 

 tlie adjacent surfaces of the maxillae. 



The most interesting lingual structures are the two basal stalks 

 (Plate 6, Figure 3S, pd.'), each of which articulates with the cardo of 

 the same side and also furnishes a firm origin for the adductors and re- 

 tractors of the first maxilla, as in Orchesella (Folsom, '99, Plate 3, Fig- 

 ure 21). The development of these stalks has never been described. 

 Although difficult to comprehend with a knowledge of the finished con- 

 dition only, it is simpler than might be expected. The key to the 

 understanding of its origin is the fact that each chitinous stalk is formed 

 in a groove which is but a longitudinal evagination of the maxillaiy 

 pocket, and follows the mesal surface of the first maxilla back to tlie 

 cardo. The base of the lingual fundament is at ba. in Figure 30 (Plate 

 5), and that of the maxilla at ba.' ; consequently the stalk is developed 

 in a superficial groove of the germ band itself — that part of the germ 

 band connecting the base of the lingua with the extreme base of the 

 maxilla. In ventral aspect at Stage 7 (Plate 5, Figure 29, 2xL'), the 

 continuity of the stalk along the surface of the maxillary pocket is evi- 

 dent. Dorsal to the stalk, of course, the base of the maxilla is connected 

 with the head, but under the connecting region passes the stalk. 



I must now explain how maxillary muscles become attached to the 

 stalk in spite of the fact that the latter is a superficial formation of the 

 hypodermis. This may be learned from transections at Stages 7 and 8. 

 hut also, and more easily, from good serial sections of an adult head, 



