56 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 39. 



apparent first abdominal tergum (IT), wliicli fits closely into the 

 concavity under the posterior edge of the metanotum. (iVs). 



The question hence 

 Mbj N, ^^ ^^j^ ^ arises, in making an 



interpretation of these 

 parts in the Orthop- 

 tera, whether the true 

 postnotum of the me- 

 tathorax has been 

 fused with the first 

 tergum of the abdo- 

 men, or whether the 

 posterior ends of the 

 dorsal muscles and the 

 phragma, when pres- 

 ent, have become at- 

 tached to the first ab- 

 dominal tergum. Since 

 the middle phragma, 

 as will presently be 

 shown, is in some or- 

 ders attached to the 

 posterior edge of the 

 mesathorax and in others to the anterior edge of the metathorax, 

 there would seem to be 

 no logical reason why the '■ ■ * 



posterior phragma should 

 not sometimes be at- 

 tached to the front of 

 the first abdominal ter- 

 gum. Woodworth (1909), 

 in fact, argues that the 

 phragmas really belong in 

 all cases to the segment 

 following them. The 

 writer, however, believes 

 that the phragmas are in- 

 tersegmental, or are com- 

 posed of lamellae derived 

 from both segments, and 

 that they become second- 

 arily more solidly asso- 

 ciated with the one seg- 



FiG. 12.— Longitudinal section through back of mesothoeax, 



METATHORAX, AND BASE OF ABDOMEN OF A LOCUST (TrIMERO- 



TROPUS maritima): Au, "auditory organ;" CxP, coxal process 

 OF metapleurum; DMcl, dorsal longitudinal muscles; Epjus, 

 epimerum of metathorax; Epss, episternum of metathorax; 



IT, FIRST ABDOMINAL TERGUM; Afbi, POSTNOTAL MEMBRANE OF 



mesothoeax; Ni, mesonotum; N3, metanotum; PA, pleural 



arm; PiVs, plate FUSED with first ABDOMINAL TERGUM (/T), 

 which is PROBABLY THE POSTNOTUM OF METATHORAX; IPh, 2Ph, 

 SPh, ANTERIOR MIDDLE AND POSTERIOR PHRAGMAS; 2Sp, SECOND 

 THORACIC SPIRACLE. 



Fig. 13.— Metathorax and abdomen of a long-horned 



GRASSHOPPER (SCUDDERIA FURCATA), SHOWING THE APPARENT 

 POSTNOTUM OF THE METATHORAX (P N3) INTIMATELY FUSED 

 "WITH THE FIRST ABDOMINAL TERGUM (IT): Cxg, METACOXA; 

 EpSz, Epmz, EPISTERNUM AND EPIMERUM OF METATHORAX; 

 /r, FIRST ABDOMINAL tergum; N3, METANOTUM; 1P,2P, 

 EPISTERNAL PARAPTERA; P N3, THE APPARENT POSTNOTUM 



OF metathorax; S3, metasternum; Tn, trochantin; 



WPz, PLEURAL WING PROCESS. 



ment or the other. Ber- 

 lese (1906) regards the plate in question in the Orthoptera as the 

 acrotergite " of the first abdominal segment, but he homologizes it 



(( 



