I 54 CONNECTICUT GEOL. AND NAT. HIST. SURVEY [Bllll. 



delicate structure called the plumule by Kiienckel d'Herculais (LSTo) 



J is borne in tliis region of the thorax. 



I The katepimeron, or "hypopleura"", l-eiii^ is faintly deniarked 



from the ui)|)er reo-ion of the epimeron above it in the tipulid shown 



I in Fig. r., A. and the katepimeron is divided into an upper and, lower 



re,gion in this insect. The epimeron, em, is not divided into an upper 

 and lower region in the culicids (Fig. 6, D), and there is no suture 

 between the upper and low'er portion of the epimeron in the myceto- 

 philids (Fig. C. B). but the lower ])ortion of the einuieron is typically 

 nmch narrower than the upper region in the mycetophilids. The 

 katepimeron, kern, does not unite with the meron, m£^ in most of the 

 tipulids (Fig. 6, A), but in the hexatouiine and eriopterine tipulids 

 (Crampton, 1925c, Plates 2 and 3), the genera NeoUvinophila^ ^'UP' 

 teria, Ormosia^ Heloh'ui, MoIophUiis and Amphineurus furnish an 

 excellent series of intergradations in wdiich the meron is quite dis- 

 tinct at first, but gradually becomes detached from the rest of the' 

 coxa, and migrates into the pleural region to fuse wath the ioweri 

 portion of the katepimeron, to form a composite region, such as thati 

 labelled in pi in Fig. G, C, called the meropleurite or meropleuron. 

 Hansen (1980) denies that such a fusion of the meron wdth the 

 anej^imeron occurs in the Diptera, but the muscles attached to the< 

 composite region bear out the evidence of comparative anatom3% which, 

 very clearly shows that such a fusion does occur; and a complete se- 

 ries of intergradations illustrating the steps in the process of fusion is- 

 to be found in several diiferent types of Diptera, so that the tipulids ' 

 mentioned above are not the only Diptera illustrating this process very) 

 convincingly to anyone who is at all familiar with the anatomy of I 

 these forms. 



When the meral region of the coxa unites wath the katepimeron, 

 as in the housefly shoAvn m Fig. C. C, the remainder of the coxa may; 

 become divided into a basal region, hex, which remains united with! 

 the region mpl, wdiile the distal region, dcx^ becomes detached to re- 

 store the mobility of the coxa when its basal region is united withi 

 the lower region of the epimeron. Malloch (1923), Shannon (1923),) 

 and others, have pointed out the value of the occurrence of thei 

 sclerite, dcx, (Fig. 6,C), or the process it bears, for indicating thei 

 relationships of the Pyr,gotidae and other higher Diptera. 



The inesothoracic meropleurite, mpl of Fig. 6, C. is usually inter| 

 preted as the ''inetasternum" in the Diptera, as is also the case witl 

 the meron, me of Fig. G, A and D, although these sclerites are somel 

 times called the "episternum" of the metathorax. In other instancesj 

 the meropleurite, mpl, (or the meron, me) is regarded as the posteriol 

 region of the mesosternum, and in such cases the dorsal portion o| 

 the epimeron, aern^ above it, is interpreted as the entire epimeron, anc 

 numerous other interpretations have l)een given for these and otheri 

 sclerites of the thorax. The real homologies of the thoracic sclerite^j 

 have been known for more than a quarter of a century, however, h\% 

 taxonomists have been unw'illing to give up the conventional termll 

 nology proposed by Osten-Sacken (1884) despite the fact that some oj 



