NO. 10 FEEDTNG ORGANS OK AKACH NIOA— SNODGRASS 



II 



ar 



Imc. 4. — Segmentation and musculature uf the arachnid Icr, anil pretarsus of 



Limulus. 



A, Mastifioproctux quianlcus (H. Lucas), Pedipalpida, end of a leg. pretarsus 

 with a median claw (/Jaf) and two lateral claws (L'>i). B, Z,«-iV)/'i<mw>m sp.. 

 Phalangida. end of pcdipalp tarsus, with simple clawlike pretarsus. C, Pandmus 

 sp., Scorpionida, distal segments of leg showing distribution of prctarsal 

 muscles. D. Ccutruroidcs sp., Scorpionida, base of tarsus, showing presence of 

 only a single tarsal muscle, a depressor {dptar), arising in tihia. E. Atcmnus 

 politux (Simon), Chelonethida, fourth leg and muscles, only one muscle {dptar) 

 on base of tarsus (from Chamberlin, 1931). F, Limulus potyphcmus I... 

 Xiphosurida, chela of a leg, both muscles of pretarsus arising in tarsus. 



IJac, dactyl (median claw); dpptar, dei)ressor muscle of pretarsus; dpt. de- 

 pressor tendon of pretarsus ; dptar, depressor of tarsus ; dptb, depressor of 

 tibia; 1-m, femur; hptar, levator of pretarsus; /:•/. levator tendon of pretarsus: 

 Ivtb, levator of tibia; Pat, patella; Ptar, pretarsus; Tar, tarsus, iTar, ^Tar, first 

 and second tarsal suhsepments ; Th. tibia; Tr. trochanter; I'u, unguis (lateral 

 ■law ). 



