1909.] 



NATURAL SCIENCES OF PHILADELPHIA. 



33 



that they should. This relation, however, does not exist, for these 

 subdivisions do not represent four annuli, as assumed by MacLeay. 

 Furthermore, there is this very serious objection to MacLeay 's termi- 

 nology, that the designation sternum cannot be applied to a subdivision 

 of the sternal region, since Audouin employed the name sternum to 

 designate the whole ventral region of the segment, and it is in the latter 

 sense that the term is everywhere used. Lastly, since MacLeay has 

 neither seen, figured nor described these regions, but merely assumes 

 their existence based ipon a fallacious hypothesis, his terminology is 

 not binding. 



Comstock, '02, although he makes no mention of MacLeay, has at- 

 tempted to apply MacLeay's terminology to the sternal region. Un- 



Fig. 18. 



Fig. 17. — Corydalis. — Ventral view of mesothorax. Sternum and pleura spread 

 out in one plane. Legs shortened. 



Fig. 18. — Hydropsyche. — Ventral view of pro- and meso-thoracic sterna and 

 pleura, spread out in one plane. Only the basal portions of the coxa- 

 represented. 



fortunately both of Comstock's figures (pp. 24 and 25) are of the 

 metathoracic segment, and what he terms the sternellum is the first 

 abdominal sternum. This accounts for the fact that he found no 

 "poststernellum." 



The Presternum.— -The name presternum is the only one of Com- 

 stock's and MacLeay's terms here adopted, since only the presternum 

 in Comstock's figure of Pteronarcys (p. 24) has a corresponding region 

 in the sternum of Nemura (pi. I, S t ). This term, however, has 

 been adopted without reference to Meinert's, '67, presternum, men- 

 tioned in his description of Japyx. 



The Japygidse are such rare insects that the writer was unable to 

 procure a specimen for dissection, and it is therefore impossible to 

 state here, with any degree of certainty, to what extent the presternum 

 3 



