COLEOPTERA 



465 



Almost the only use that has been made of the characteristics of 

 the wings has been restricted to certain features of the elytra, those 

 that can be seen with- 

 out spreading the 

 wings. These are the 

 shape of the elytra, 

 the presence or ab- 

 sence of striae, the pres- 

 ence or absence of 

 punctures and their 

 distribution when 

 present, and the pres- 

 ence or absence of setae, 

 pubescence, or scales 

 on the surface of the 

 elytra. A beginning has 

 been made, however, 

 to make use of the 

 venation of the hind 

 wings; this, as yet, is 

 restricted to an indi- 

 cation of the type of 

 wing-venation charac- 

 teristic in each case of 

 the superfamilies. 



The venation of 

 the wings of the Cole- 

 optera has become 

 greatly modified, and, 

 consequently, the de- 

 termination of the ho- 

 mologies of the wing- 

 veins is a difficult mat- Fig. 545.— Ventral aspect of a beetle, Enchroma gigan- 

 ter The transforma- /ea; ^, prothorax; 5, mesothorax; C, metathorax; 

 4.- r +V, f • c, c, c, coxae; em, em, em, epimera; es, es, es, epis- 



tion Ot tne tore wmgS terna; s, s, s, sterna; /, /, trochantins; x, elytrum; 

 into elytra has result- y, antecoxal piece of metasternum. 

 ed in a great reduction of their venation; and the foldings of the hind 

 wings interrupt the veins and cause distortions in their courses. 



It is only recently that extended studies of the wing-venation 

 of the Coleoptera have been made, and the conclusions reached by 

 the different investigators are not fully in accord. But much progress 

 has been made, and so much interest is being shown in the subject 

 that we can confidently expect that conclusions will soon be reached 

 that can be generally accepted. 



Among the recent studies of the subject is an extended one by 

 Dr. Wm. T. M. Forbes ('22 b), in which the venation of the hind wings 

 of more than fifty species of beetles are figured. The accompanying 

 fig;ures (Figs. 546-547), copied from Dr. Forbes' paper, will serve to 

 illustrate his conclusions regarding the homologies of the wing-veins 



