50 CONNECTICUT GEOL. AND NAT. HIST. SURVEY [Bull. 



not be given to the occurrence of this small area in the postscutellum. 

 Curran (1924) proposes the name "metascutellum" for the mesotho- 

 racic siibscutellum, ssl of Fig. 6, C. but the true metascutellum is the 

 scutellum of the metathorax, which is an area of the metanotum; 

 and from the morphological standpoint, it is inadvisable to apply 

 the designation ''metascutellum'" to any structure other than the true 

 scutellum of the metathorax, so that it is preferable to designate the 

 sclerite below the mesoscutellum as the siibscutellum. 



It is very unfortunate that the erroneous interpretation of the 

 parts of the mesothoracic postscutellum proposed more than a century 

 ago by Westwood (1832) and others, became so firmly established in 

 the literature that even the influence of Brauer (1882) was insufficient 

 to cause it to be discarded; and many taxonomists still cling to the 

 old familiar misinterpretations, despite the fact that students of com- 

 parative morphology in this country and abroad have repeatedly 

 shown that these interpretations are wholly untenable. Westwood 

 ( 1832) considered that the mesothoracic inediotergite, w/ of Fig. 6, A, 

 B, C, t^tc, is the scutum of the metathorax, and interpreted the meta- 

 notum, mtn, as the scutellum of the metathorax, although he rejected 

 the idea proposed by Latreille (1821-1825) that the metathorax of 

 the Diptera represents the median segment of the Hymenoptera (and 

 that the halteres are abdominal appendages). Although he was ac- 

 quainted with the observations of Hammond (1881), who had shown 

 that the niediotergite, mt of Fig. (5, A, B, C, etc., is a part of the 

 mesothoracic postscutellum, Osten-Sacken (1884) appears to adopt 

 the designation ''metanotum'' for the niediotergite, m,t, in his fiflny'' 

 of the parts taken from t>-« p^p^^ ^y 3int (isoii) and designates the 

 lateral portion of the mesothoracic postscutellum, labelled spt and fpf 

 in Fig. 6, A. C, etc., as the "metapleura'', which, he says, corresponds 

 to the callus metanoti lateralis of Loew (1862). 



Brauer (1882) calls the sclerite, ssl of Fig. 6, C, the ''postscutel- 

 lum", and interprets the sclerite, mt, as the mesophragma (i. e., the 

 mesothoracic postphragma). He appears to think that the sclerite, 

 spt of Fig. 6, A, is a portion of the mesothoracic epimeron, and sug- 

 gests that the sclerite. ipt, may represent the metathoracic episternum, 

 or even the prescutum of the 'metathorax. The lateral regions of the 

 postscutellum (ptg, spt and ij^t of Fig. 6). however, are recognized 

 as such by all of the recent students of comparative morphology, 

 such as Snodgrass (1909), Crampton* (1925-1926), Young (1921), 

 Comstock (1924). Weber (1933), etc., who are unanimous in inter- 

 preting the sclerite, psl, as the mesothoracic postscutellum in the 

 Dipter^. Curran (1934), however, is evidently expressing the opinion 

 of many of the taxonomists when he states, in a footnote to page 

 487, that he is "far from being convinced that the metanotum, as used 

 by taxonomists is actually part of the mesonotum : there is a distinct, 



^he d.-velo7ment of Protoplasa (see Crampton. 1930, p. 88, and Plate 3) which is 

 one of^ the most primitive representatives of the order Diptera, very olearly shows 

 that the postscutellum develops from the mesothoracic region m front of the tiue 

 metanotum which bears the wing-like cases of the halteres in the pupa of this 

 archaic form. 



