380 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



EXPLANATION OF PLATES. 



All figures were drawn with the aid of the camera lucida from preparations of 

 Thi/malus mar(jinicollis Chevr. The magnifications are given witii the descriptions 

 of the several figures. 



In Plates 1-5, Figures 1-5, 7, 0, and II are drawn from reconstructions of serial 

 sections. They form two series of figures illustrating the anatomical clianges of 

 the dorsal antero-posterior (Figs. 1, 2) and lateral dorso-ventral (Figs. 3-5, 7, 9, II) 

 groups of metatlioracic muscles during metamorphosis. These figures are all 

 magnified 67.5 diameters. 



ABBREVIATIONS. 



aa. Colin .... Cohnheira's areas. 



al Wing. 



cd.n Nerve cord. 



chr Chromatin masses left after tlie disintegration of nuclei. 



cl.mit Tracheal cells in stages of mitotic division. 



cl. tr Traclieal cell. 



cl. tr.^ Tracheal cells showing connections with tracheae. 



cl. tr.'^ Tracheal cells whose connections with the tracheae have 



been severed, but which show tracheoles througli their 



cytoplasm. 



cl. tr.^ Tracheal cell entirely embedded in the muscle. 



cp. adp Fat body. 



cr Heart. 



eta Cuticula. 



dep. trg Depressor tergi. 



elif Elytron. 



e'stn Musculus episternalis. 



e'th Epithehal lining of the foreintestine. 



ext. al. mag. mt'thx. . Extensor alae magnus metathoracis. 



ext.al.pa.mt'thx. . E.xtensor alae parvus metathoracis. 



ext. cox. mt'thx. (^-3) Extensor coxae metathoracis (primus, secundus, tertius). 



ext. trchn. int'tkr. . . Extensor trochanteris metathoracis. 



Jlx. al, mt'thx. (1-^) Flexor alae metathoracis (primus, secundus, tertius). 



Jlx, cox. mt'thx. (-^-5) Flexor coxae metathoracis (primus, secundus, tertius, quat- 



tuor, quintus). 



