1917] Veracervix or Neck Region In Insects 195 



The term collum is applied to the narrow posterior portion 

 of the head region or to the entire prothorax, by Coleoptero- 

 logists, and the designation jugulum is applied to the gular 

 region of the head, or to the sides and sternum of the prothorax, 

 so that neither of these terms is available for the true neck 

 region. Since the neck plates are universally designated as the 

 cervical sclerites, the term cervix would be singularly appropri- 

 ate for the region in question. Dipterologists, however, have 

 very inconsiderately applied the term cervix to the upper 

 portion of the hinder head region in certain flies, and the same 

 term is applied to the posterior constricted neck-like region of 

 the head in other insects, in which the true neck region is also 

 present, so that it would merely create confusion to apply 

 the designation cervix to the true neck region. In order to 

 preserve some form of the term cervix, which is implied in the 

 universally accepted designation cervical sclerites, the neck 

 region was referred to as the veracervix or "cervicum" (Cramp- 

 ton, 1908-1914, Snodgrass, 1910, Martin, 1916) and the former 

 term has been retained in the present paper. 



The intersegmental plates between the other thoracic 

 segments are aot preserved in many Pterygotan insects. Traces 

 of them occur between the prothorax and mesothorax of 

 Corydalis cornittiis, between the prothorax and mesothorax 

 of the earwig Dorii luteipennis (the unknown Forficulid shown 

 in Plate 3, Fig. 19, by Crampton and Hasey, 1915), and in 

 certain Plecoptera and Homoptera. It is in the Apterygotan 

 forms, however, such as Japyx and Eosentomon (Fig. 1) that the 

 intersegmental plates are best preserved between the thoracic 

 segments, and since these are among the most primitive of 

 living insects, we are justified in assuming that the conditions 

 which they present approximate the original one, in many 

 respects. 



In Japyx and Eosentomon (Fig. 1) the eutrochantin 'T' 

 intervenes between the coxa and the pleural plate "pi/' This 

 condition is preserved in the prothoracic region (i. e. in the non- 

 wing-bearing segment, w^hich is consequently the least modified 

 and the most like the segments of the Apterygotan forms) of 

 many of the most primitive Pterygotan forms such as the 

 Plecoptera, Embiids, certain Forficulids (Allostethus) Gryllo- 

 blattids, Termites, etc., so that I would now consider this 

 condition as representing the original one, and have therefore 



