1911.] NATURAL SCIENCES OF PHILADELPHIA. 417 



neu. n neuroglia nuclei. s. f sensory fiber. 



neu- w neuroglia walls. sk socket. 



nuc. c nuclei of hypodermal cells. si slit. 



o. m outer membrane of hypo- s. s single slit. 



dermis. t. h fixed tactile hair. 



r. m reflexor muscle. v. sin venous sinus. 



sar sarcolemma. 1. 1. a first line of articulation. 



s. c sense cell. 2. 1. a second line of articulation. 



s. c. n sense cell nucleus. 



Plate XXX. — Fig. 1. — Cross section of distal end of trochanter of Agalena ncevia 

 just moulted, showing the anatomy of the leg and the innervation of a 

 large lyriform organ. The cuticula is only diagrammatic as taken from 

 various species. The nerve is drawn at the location it holds when its 

 branch penetrates the basement membrane of the hypodermis, although 

 this branch begins to leave the nerve 220 microns in front of this place. 

 The sense cells have their natural position, but they have been recon- 

 structed from nine sections just in front of where the nerve branch enters 

 the hypodermis. All other parts are taken from just one section in front 

 of the organ. Leitz oc. 2 and obj. 7. X 290. 

 Fig. 2. — Diagram of a longitudinal-transverse section of the distal end of 

 the femur of Th. tepidariorum, showing the anatomy of the leg and the 

 innervation of the following: a lyriform organ, a fixed tactile hair, a 

 movable tactile hair, and the two muscles of the latter hair. All the 

 larger hairs are more or less movable, while the smaller ones are non- 

 movable. 



Plate XXXI. — Fig. 3. — Two sense cells as they actually appear in a cross sec- 

 tion of a trochanter of Th. tepidarioriim six or seven hours after moult- 

 ing. Zeiss comps. oc. 6 and oil imm. 12. X 960. 



Fig. 4. — Diagram showing a single slit of a lyriform organ with its sense 

 cell attached at the bottom of the dilatation. 



Fig. 5. — Reconstruction from two consecutive sections of the trochanter 

 of Th. tepidarioriim six or seven hours after moulting, showing the inner- 

 vation of a single slit. Zeiss comps. oc. 6 and oil imm. 12. X 960. 



Fig. 6. — The innervation with fragments of two muscles of a movable 

 tactile hair from the distal end of the femur of Th. tepidariorum six or 

 seven hours after moulting. The hypodermis is pulled away from the 

 cuticula. Leitz oc. 4 and obj. 7. X 720. 



Fig. 7. — The innervation of two fixed tactile hairs on the trochanter of 

 Pholcus. The nerve is considerably torn. Leitz oc. 2 and obj. 7. X 455. 



Fig. 8. — Same as fig. 6, except a much smaller hair. Here the muscles are 

 distinctly shown, but the sense cell is absent. Zeiss comps. oc. 6 and 

 oil imm.' 12. X 960. 



Plate XXXII. — Fig. 9. — a ventral and b dorsal surface of the palp of a male 

 Troglohyphantes, showing the single slits on the sixth joint. The bulb 

 with its accessaries are omitted. Leitz oc. 2 and obj. 3. X 50. 



Fig. 10. — Organ No. 13 on metatarsus of second leg of Th. tepidariorum. 



Figs. 10-12 and 15-58. X 385. Zeiss comps. oc. 6 and Leitz obj. 7. 



Fig. 11. — The extremely large organ on cheliceron of Moggridgea. 



Fig. 12. — Organ on tibia of third leg of Uroctea. 



Fig. 13. — Ventral view of Th. tepidariorum, showing disposition of lyriform 

 organs. The legs are slightly too short and the last two pairs are turned 

 over so that their dorsal surface is shown. The spider is enlarged about 

 five, while the lyriform organs are enlarged about seven times. 



Fig. 14. — Same as fig. 13, except here the doisal view is shown and the last 

 two pairs of legs are turned over so that they show their ventral surface. 



Plate XXXIII. — Fig. 15. — Organ No. 3 from trochanter of fourth leg of Th. 

 tepidariorum . 



