46 PROC. ENT. SOC. WASH., VOL. 20, NO. 3, MAR., 1918 



only two of the original sternal plates here recognized, namely 

 the basisternum and furcasternum. 



Berlese, 1906-1909, has made an unfortunate attempt to apply 

 the terms prosternite, mesosternite and metasternite (which should 

 be restricted to a sternite of the prothorax, mesothorax or meta- 

 thorax respectively) to subdivisions of one and the same segment. 

 This application of the prefixes pro, meso, and meta, to sclerites of 

 segments other than the one indicated by the prefix in question, is 

 wholly inadmissible, and if adopted, would lead to endless confusion. 

 Fortunately, however, the regions to which Berlese applies these 

 terms do not represent the true subdivisions, in most instances, 

 and therefore have no bearing upon the interpretation of the sub- 

 divisions here discussed. Thus, in his figure 204 of a Dytiscus 

 larva, Berlese refers to the anterior sclerite ps of fig. 3 (i.e., the 

 presternum) as the acrosternite, and calls the space between it 

 and the basisternum (bs of fig. 3) the "prosternite." The basi- 

 sternum of figure 3, 6s, he designates as the "mesosternite," 

 while the furcasternum fs and the spinasternum ss together are 

 termed the "metasternite" by him. In other cases, his applica- 

 tions of these terms is so varied, that it is impossible to determine 

 to which sternites he intends that they should refer in general. 



Assuming that the two hypothetical subsegments postulated 

 for each segment by Comstock and Kochi, 1902, actually exist, 

 Berlese adopts Comstock's designations "sternum" and sternel- 

 lum for the ventral regions of these imaginary subsegments, and 

 states that his acrosternite and "prosternite" together compose 

 the sternum of Comstock's terminology, while his "mesosternite" 

 and "metasternite" together make up the sternellum of Com- 

 stock's terminology. Berlese's method of employing the terms 

 "sternum" and sternellum, however, is very different from those 

 employed by his predecessors, and his application of the terms 

 is so varied as to greatly increase, instead of clearing up, the 

 chaotic confusion in the usage of these terms, thus forcefully 

 illustrating the fact that it is quite impossible to designate homol- 

 ogous plates by the same term in every case unless some descrip- 

 tive terms such as furcasternum for the furca-bearing sternite, 

 spinasternum for the spiina-bearing sternite, etc., are used. 



On page 171, in describing the condition found in the meso- 

 and metathoracic sternal regions of an adult Dt/tiscus, shown 

 in his figure 167, Berlese states that in this figure the plates 

 labeled "7s" (which are really the subspiracular plates and the 

 spinasternum of the prothorax i. e., ip and ss of fig. 74) represent 

 the "sternum" of the mesothorax. On the other hand, the plate 

 which he designates as the " sternellum " of the mesothorax in his 

 figure 167 is the true mesosternurn, while the structures which 



