BREED : METAMORPHOSIS OF THE MUSCLES OF A BEETLE. 333 



The remaining muscles of the lateral dorso-ventral group are all leg 

 muscles, either flexors or extensors. The homologies with the muscles 

 of Dytiscus are not all entirely certain, because the leg muscles of Dy- 

 tiscus are so different from those of Melolontha and Thymalus, that 

 the homologies are not always evident. 



Flexor coxae metafhoracis primus. 

 (Premier flecMsseur de la Tianche of Straus-Diirckheim ; extensor trochan- 



teris metathoracis of Luks.) 



This muscle is found in the larva (Plate 1, Figure 4, Jlx. cox. mftJix. l) 

 as one fibre, whose origin is on the ventral portion of the suture between 

 the metathorax and the abdomen, and whose insertion is on the outside 

 surface of the leg on a portion which later forms the coxa of the adult. 

 In the piqm (Plate 3, Figure 7, fix. cox. mftlix. 1) its position is changed 

 greatly by the formation of the metafurca, and the shifting of the leg 

 posteriorly. The origin of this muscle in the imago (Plate 5, Figure 11, 

 fix. cox. mt'thx. 1) is on the posterior part of the median lamina of the 

 metafurca {mffur. 4), and its insertion, on the anterior ventral edge of 

 the coxa about one third of the distance from the trochanter to the 

 lateral edge of the coxa. 



For an account of Flexor coxae metathoracis secundus, see page 325, and 

 for an account of Flexor coxae metathoracis tertius, see page 326. 



Flexor coxae metathoracis quattuor. 

 (Quatrieme fiechisseur de la hanche of Straus-Durckheim ; Jlexor alae 



metathoracis of Luks.) 

 This is the second muscle of the imaginal metathorax which has not 

 been found in the larva. It is found in younger pupae than is the first 

 muscle (musculus episternalis), but it is probably a muscle of new forma- 

 tion in the pujm (Plate 2, Figure 5, fix. cox. mt'thx. 4). In the imago 

 (Plate 4, Figure ^, fix. cox. mfthx. 4) it takes its origin near the middle 

 of the dorsal side of the episternum, and, extending caudad and a little 

 ventrad, is inserted on the extreme anterior lateral edge of the coxa. 

 This is the muscle which Luks has incorrectly described for Dytiscus as 

 the flexor of the wing. 



Flexor coxae metathoracis quintus. 

 {Cinquieme fiechisseur de la hanche of Straus-Diirckheim ; musculiis 



furcae dorsalis of Luks.) 

 The fifth metathoracic flexor of the coxa is found in the larva (Plate 1, 

 Figure 4, fix. cox. mt'thx. 5) as a single fibre, extending from the latero- 



