SPINNING APPARATUS OP GEOMETRIC SPIDERS. 39 



EXPLANATION OF PLATE V, 



Illustrating Mr. Cecil Warburton's paper on " The Spinning 

 Apparatus of Geometric Spiders.^' 



Fig. 1. — Profile of Epeira diademata, sp. spinnerets. 



Fig. 2. — Ventral aspect of the same species. 



Fig. 3. — Ampullaceal gland. 



Fig. 4. — Aggregate gland. 



Fig. 5. — Tubuliform gland. 



Fig. 6. — Piriform gland. 



Fig. 7. — Acinate gland. 



Fig. 8. — External spinning organs at rest. a. Anterior, p. Posterior 

 spinnerets, t. Anterior tongue-like fold, z. Terminal fold of abdomen. 



Figs, 9 — 13 show the composition of the " trailing-line " under various 

 circumstances, i. Intermediate spinnerets. 



Fig. 14. — Stages in the formation of the viscid globules, d. Shows the 

 final arrangement. 



Fig, 15.— Teased spiral line, showing that the "ground-line " is double. 



Fig, 16. — "Attachment disc" (Haftscheibe, Apsteiu), 



Fig. 17. — The same, more in profile. 



Fig. 18. — Attachment disc, gluing together irregular strands which held 

 an egg-cocoon in position. 



Fig, 19. — Section (somewhat diagrammatic) of aggregate gland at rest. 



Fig, 20. — Ditto of aggregate gland when the spider had just constructed 

 its web, (The right half only of Figs. 19 and 20 is shaded.) 



