PROC. ENT. SOC. WASH., VOL. 20, \<>. :{, MAR., 1918 49 



lateral wings forms the laterosternites Is of figs. 14, 15, text-fig. 

 1, etc.) should supplant the designation "sternum" used in the 

 restricted sense. Snodgrass, 1910, however, substitutes the 

 term "eusternum" for the third sternal subdivision, without 

 giving any reason for so doing; but, since he has applied his terms 

 to no actual sclerites in any insect (other than the use of the 

 terms presternum? " sternum " and sternellum cited above) it 

 is impossible to determine to what sclerites his terms should 

 be applied, and the designations presternum, basisternum, 

 furcasternum, and spinasternum remain as the only terms 'actually 

 applied to the consecutive sternal subdivisions figured or de- 

 scribed in any insect, and they are the only terms which can be 

 used without specifying that they are employed in this or that 

 sense, and not as applied by this or that entomologist! Further- 

 more, since such terms as furcasternum and spinasternum could 

 not possibly be applied to the wrong sternites (since the names 

 imply that the sternite in question bears the furca or spina), 

 it is preferable to employ these purely descriptive terms. 



The advisability of using purely descriptive terms is at once 

 apparent, if we consider the possibility that the sternite ss of 

 figure 14 (i.e., the spinasternum) may prove to be the anterior- 

 most sternite of the segment behind it, instead of. being the 

 posteriormost sternite of the segment in front of it (as here given) 

 for the musculature would admit of such interpretation, and the 

 fact that in the mesothorax .of Corydalis the so-called spinaster- 

 num of the prothorax is attached to the front of the mesosternum, 

 instead of being associated with the pro thoracic region, points 

 to the possibility of the spinasternum being the anteriormost 

 sternite, as also does the fact that it is located between the sub- 

 spiracular plates which are portions of the segment behind them 

 instead of the segment in front. If it should thus be the anterior- 

 most sternite of the segment behind it (from an embryological study 

 of the formation of the spinasternum), the designation "poststcr- 

 iium" or "poststerncllum" would hardly be appropriate, while 

 the purely descriptive term spinasternum would be equally 

 applicable in either case. It is also evident that it is inadmissi- 

 ble to apply the same set of terms to entirely different sclerites 

 in adults and larvae when it is perfectly possible to homologize 

 the sclerites in all stages. Since Hopkins, 1909, has applied the 

 terms stemelluni and poststerncllum, etc. to subdivisions of the 

 basisternum and furcasternum alone of the si emit es, in adult 

 Goleoptera, these terms should Ue applied to homologous regions 

 in larval Coleoptera also, if used at all, and therefore cannot 

 be applied to the regions here recognized, which are not subdivi- 

 sions of the basisternum and furcasternum. This, however, 



