NO. 2 THORACIC MECHANISM OF A GRASSHOPPER SNODGRASS IO9 



Pcx, precoxal bridge. 



Ph, phragma. iPh, 2Ph, jPh, first, 



second, and third phragmata. 

 PI, pleuron. 

 pi, pleural sclerites between tergum 



and subcoxa. 

 PIA, pleural apophysis. 

 Pin, planta. 

 PIR, pleural ridge. 

 PIS, pleural suture. 

 PA^, postnotum. 



PNP, posterior notal wing process. 

 Poc, postocciput. 

 PoR, postoccipital ridge. 

 Ppct, prepectus. 

 Ppt, periproct. 

 PR, prescutal ridge. 

 Pra, preanal area of wing. 

 Ps, presternum. 

 ps, prescutal suture. 

 Psc, prescutum. 



PT, posterior arm of tentorium. 

 Ptar, pretarsus. 

 Ptr, peritreme. 

 Pzv, postalar arm of postnotum. 



Q, coxal branch of depressor muscle 

 of trochanter. 



R, radius. 



Rd, posterior fold, reduplication, of 

 tergum. 



S, levator muscle of tibia 



sternum. 

 SA, sternal apophysis. 

 Sa, subalare. 



sa, external pit of sternal apophysis. 

 Sc, subcosta. 

 Scl, scutellum. 

 scl, subdivision of scutellum. 



Set, scutum. 



set, subdivision of scutum. 



Sex, subcoxa. 



SI, sternellum. 



Sp, spiracle. Sp-i, Sps, first and second 



thoracic spiracles. 

 Sp)i, spina. 



spn, external pit of spina. 

 Ss, spinasternum. 

 St)i, primary segmental sternite. 



T, depressor muscle of tibia. 



tergum. 

 Tar, tarsus. 

 Tb, tibia. 



tg, tegular rudiment. 

 TniMel, tympanal muscle. 

 T)i, trochantin. 

 Tr, trochanter. iTr, 2Tr, first and 



second trochanters. 

 Tra, trachea. 



(/, levator muscle of tarsus. 

 Uf, unguifer of tarsus. 

 Un, unguis, claw. 

 Utr, unguitractor plate. 



i\ depressor muscle of tarsus. 

 VD, vena dividens. 

 VIIISp, eighth abdominal spiracle. 

 VMel, ventral longitudinal muscle. 

 VR, ridge between scutum and scu- 

 tellum. 

 vs, scuto-scutellar suture. 



W, wing. 



WP, pleural wing process. 



X, depressor muscle of pretarsus, re- 

 tractor of claws. 



REFERENCES 



Bauer, A. (igio). Die Muskulatur von Dytiscus marginalis. Zeitschr. wiss. 



Zool., 95:594-646, 19 figs. Also in Korschelt (1924), Chapter 12. 

 Becker, E. (1923). Zum Bau und zur Genese des coxotrochanteralen Teiles 



des Ateloceratenbeins. Zool. Anz., 57: 137-144, 4 figs. 

 (1924). Zur morphologische Bedeutung der Pleuren bei Ateloceraten. 



Zool. Ana., 60: 169-185, 6 figs. 

 Berlese, a. (1909). Gli insetti, Vol. i. Milan. 



