March, 'ogl ENTOMOLOGICAL XKWS. TOT 



that the artificialness of this scheme appears. On the specimen 

 it is clear that the median tongue on the floor of the groove 

 (fig. i, G) belongs to the part behind it and is separated from 

 the areas at each side of it. This is further confirmed by a 

 study of the ventral surface (fig. 2). Yet Audouin makes 

 this the body of a bat-shaped sclerite in which the lateral areas 

 represent the two wings. Finally, the only part that is distinct 

 and absolutely a separate sclerite in nature is the plate desig- 

 nated pseudonotum (PN) in figures I and 2. Yet Audouin 

 represents this as an integral part of the median region of the 

 posterior notal subdivision in front of it! This combination 

 he terms the posts cut ellum (pscl). A common sense separa- 

 tion of the plates along natural sutures could never produce 

 such a plan of organization as figure 3. 



This criticism should be directed not against Audouin so 

 much as against those present day entomologists who have 

 contentedly copied Audouin's drawings instead of examining 

 the subject for themselves. Furthermore a study of the works 

 of modern insect morphologists who attempt to establish 

 the quadruple tergal theory for all insects, as Berlese (1906), 

 shows that this can be done only by a free use of the imagina- 

 tion in laying clown lines where nature has neglected to do so. 



Now, although we are forced to discard Audouin's historic 

 illustration of the four divisions of the tergum, yet his terms 

 prescutum, scutum scutellwn and postscutellum are very con- 

 venient ones to retain, for it is true that in a very large num- 

 ber of insects especially in all of the higher orders, four fairly 

 well marked tergal subdivisions are present. To what extent 

 these subdivisions occur the writer will attempt to show in a 

 future paper on the insect thorax. But, though they are of 

 very general occurrence, they are purely secondary and, in 

 most cases are not homologous in the different orders. They 

 are best developed in the Lepidoptera, Hymenoptcra and Dip- 

 tera. As has already been stated the transverse ridge on the 

 ventral surface of the Coleopteran tergum (fig. 2, w) does not 

 exist in the other orders. Hence, we may regard the subscler- 

 ites 2 and 3 (fig. i) as secondary divisions of one original area. 

 Then we can re-apply Audouin's names as follows: region i, 



