152 PROC. ENT. SOC. WASH., VOL. 24, NO. 6, JUNE, 1922 



muscles are inserted, is distinct all around from the clypeus, 

 instead of being united mesially with this plate as in mandibu- 

 lata (fig. 3). 



Melanderia mandibulata, of the coast of Washington, boldly 

 goes to the logical extreme and has the jaw lobes of its labella 

 developed into well-formed, tapering, sharp-pointed organs of 

 true mandibular form. 



We have here, evidently, a case of species badly in need of 

 jaws, but, mandibles having been lost by their ancestors, and 

 irrevocably, the family has developed substitutes for these organs 

 in the form of prongs and hooks on the epipharynx, while 

 Melanderia has supplemented these with special jaw-like lobes 

 of the labellum. 



REFERENCES. 



1888. Langhoffer, A. Beitrage zur Kenntniss der Mundtheile der Dipteren. 



Inaugural Dissertation, Jena, 32 pages. 

 1902. Langhoffer, A. Mandibulae Dolichopodidarum. Verhandlungen des 



V Internationalen Zoologen-Congresses zu Berlin, 1901, pp. 480- 



486, 4 figs. 



EXPLANATION OF PLATE 14. 



Melanderia mandibulaia Aidrich. 



Fig. 1 Facial view of head with "mandibles" open. 



Fig. 2 Side view of head with "mandibles" (b) closed and concealed beneath 



upper lobes (a) of labellam. 

 Fig. 3 The clypeus (Clp), labrum (Lm), epipharynx (Ephy) and hypopharynx 



(Hphy) removed from rest of head and labium along the line (g), 



exposing the sucking pharynx (Phy) and its dilator muscles (PhyMcl). 

 Fig. 4 The labrum and epipharynx, with clypeus, pharynx and hypopharynx 



removed, exposing the epipharyngeal apodeme (d) and its muscles 



(Ephy Me!) attached to basal plate (x) of labrum. 

 Fig. 5 The epipharyngeal armature and apodeme (d) with muscles removed. 



The four epipharyngeal prongs (Ephv) separated and shown arising 



from two basal plates (e and/) beneath labrum, which is removed. 



The second plate (/) carries the apodeme (d) between bases of prongs. 

 Fig. 6 Side view of labium, showing basal plate (Th), and the three lateral 



divisions of the labellum (a, b and c), the middle one strongly chitinous 



and mandible-like. 



a, upper lateral lobe of labeilum; b, jaw-like lobe of labellum; c, lower basal 

 lobe of labellum; Clp, lower part efface, probably the clypeus; d, epipharyngeal 

 apodeme; c, basal plate of anterior epipharyngeal prongs; Ephy, epipharynx;/, 

 basal plate of posterior epipharyngeal prongs; g, epipharyngeal apodeme; 

 Hphy, hypopharynx; Phy, pharynx; PhyMcl, dilator muscles of pharynx; Pip, 

 maxillary palpus; Th, theca; x, plate between labrum and clypeus, probably 

 basal part of labrum. 



