OF WASHINGTON, VOLUME XVI, 1914 159 



the larvae, justify separate family rank for the Eriocranidae and 

 the Micropterygidae of which the latter are by far the more ances- 

 tral, as shown in the following comparison of their head structure. 



The adult Micropterygid (Micropteryx ammanella Hlibner, is 

 used in this comparison), has true, well developed, strongly chi- 

 tinized, functional mandibles (fig. 35). These are in a general 

 way similar to those just described in the Eriocranid pupa, but 

 are much contracted. They have well developed fossa and con- 

 dylus, jointed on the mouth-frame and are moved by strong ab- 

 ductor and adductor muscles. Their outer end is sharply cut off 

 and palmate as in the Eriocranid pupa and toothed on the edges. 

 The upper one of the outer teeth is more pointed and larger than 

 the rest. 



In the adult Eriocranid (Mnemonica auricyanea Walsingham) 

 are found by dissection similar but rudimentary and unchitinized 

 mandibles (figs. 27, 31, 33). These have not the palmate apex, 

 and the fossa and condylus are hardly discernible, while the liga- 

 ment connecting frhem to the mouth frame is large and cushion- 

 like. In the pupa these mandibles are plainly visible within the 

 base of the pupal mandibles (fig. 14), and they possess strongly 

 developed abductor and adductor muscles (fig. 31), identical with 

 those in the pupa. These muscles and the development within 

 the corresponding pupal structure definitely prove the mandibu- 

 lar nature of these organs. 1 The presence of true biting mandibles 

 in the Micropterygidse is therefore not of such fundamental im- 

 portance as Sharp, Tutt, and others have assigned to it, the less 

 so as rudimentary mandibles may be distinguished in certain 

 much higher Lepidoptera. 2 But the further presence of all the 



1 Compare Chapman's statement, above quoted, in footnote, page 15(i-7, 

 which has been accepted by subsequent writers, as Sharp and Meyrick. 

 The former states, page 308 in his textbook, (The Cambridge Natural His- 

 tory, vol. vi, Insects, part n, 1899), "The opinion entertained by \Valter 

 that Micropteryx proper, (his 'hohere Micropteryginen,' Meyrick's 'Erio- 

 cranianaV) also possesses rudimentary mandibles is considered by Chap- 

 man, no doubt with reason, to be erroneous." Further in the same man- 

 ual, p. 437; "All the information we possess points to profound distinctions 

 between Micropteryx, (our 'Eriocranidse'), and Erioccphala, (our 'Microp- 

 terygidae,' Walter's 'niedere Micropteryginen') for whereas, in the former 

 the mandibles drop off from the pupa, so that the imago has no mandibles, 

 in the latter, the mandibles exist." Meyrick, in his monograph of tlm 

 Micropterygidae (Genera Insectorum, 912, p. 3), simply states in the diag- 

 nosis of his subfamily Eriocranince, "No mandibles." On the other hand, 

 it should be noted that Alfred Walter in his excellent work on the morphol- 

 ogy of the Lepidoptera, (Jenaische Zeitschrift fur Nalurwisscns., Bd. 18, 

 1884, neue Folge Bd. u, p. 751-807, 2 plates), has correct!}' interpreted these 

 structures in what he calls the "hohere Micropterygidae." 



2 The weak and functionless mandibles have been recognized later by 

 Kellogg, (The Mouthparts of the Lepidoptera, Am. Nat. vol. 29, p. 546, 

 1895), by Packard, (On a new Classification of the Lepidoptera, Am. Natur. 



