40 PROCEEDINGS OF THE ACADEMY OF [Jan.. 



are a number of plates which serve to strengthen its walls, and furnish 

 an articulation for the head (pi. Ill, C sv C s2 , etc.). The number of 

 these sclerites varies greatly, being the most numerous in the Orthop- 

 tera, while in certain Coleoptera they are entirely wanting. 



The neck region has been designated as the "Mikrothorax" by 

 Verhoeff, '02, who at first considered this as a fourth segment of equal 

 rank with the pro-, meso- and meta-thorax. < There appear to be very 

 grave doubts as to the correctness of this view, and' since every inves- 

 tigator who has dealt with this subject terms the region in question the 

 "neck," "Nacken," "cou," etc., according to the language in which 

 the article is written, it seems preferable to designate the neck by the 

 Latin term cervicum — a purely typographical designation, and one 

 which is already implied in the expression "cervical plates," applied 

 to its sclerites for more than eighty years. As has been stated, Ver- 

 hoeff, '02, terms the cervicum the "Mikrothorax," and at first con- 

 sidered it a fourth thoracic segment similar to the pro- meso-, and 

 meta-thorax. Later, however, he designated this "Mikrothorax" as 

 one of the so-called complementary segments (" Vordersegmente") 

 which he states can be found in front of each chief segment of the 

 thorax; and, in addition, he described the remains of an intercalary 

 segment in front of each of the above-mentioned thoracic segments. 



In the earlier works there has been much speculation as to the origin 

 of the cervical sclerites, and the question is still a very hotly debated 

 one. 



The first of these theories is that of Strauss-Durkheim, '28, who 

 states that in the neck region of the Forficulidse, one can find traces 

 of the sterna and pleura of two segments formerly existing between 

 the prothorax and the head. He had thus long ago expressed exactly 

 the same theory, founded upon the same insects, that Verhoeff uses to 

 illustrate his microthorax theory, yet Verhoeff states that "es klingt 

 zwar sonderbar, dass bei den von Hunderten von Forschern studierten 

 Insekten dergleichen (d. h. ein vorn am Thorax befindliches bisher 

 ubersehenes segment) noch gefunden werden soil, ist aber tatsachlich 

 so." 



The second theory is that of Huxley, '85. In describing the neck 

 plates he says: "I think it is probable that these cervical sclerites 

 represent the hindermost of the cephalic somites" — in other words, 

 he regards the cervicum as the labial segment. Comstock, '02, adopts 

 this view, and proposes that the appendages of the cervicum are the 

 second maxillae which leave their segment and, migrating forward, fuse 

 to form the labium. He likewise makes use of Carriere's, '98, theory, 



