— Plate 2g. — 



Figs. 1-13. — Utricidaria. 



Fig. I. — Diagrammatic representation of the histology of the door. 

 Above, view en face of the door seen from the inside of the trap; 

 below, section through a-b. 

 Fig. 2. — Sagittal section of the door: 7, upper hinge; 2, middle area; 



5, central hinge; 4, middle piece; cut, cuticle; eel, cellulose. 

 Fig. 3. — Cells of the inner course of a portion of the door, the central 

 hinge approximately in the middle; the bases of the tripping bristles 

 shown in dotted lines. Numerous props. 

 Fig. 4. — Transverse section of the threshold at the middle point, showing 



the velum. The- posture of the door edge in broken lines. 

 Fig. 5. — Section through the lateral reach, near its outer end, of the 

 threshold in U. purpurea. The posture of the door thrusting against 

 the pavement indicated by the oblique arrows. The direction of 

 water pressure against the door and velum shown by the arrows 

 below. 

 Fig. 6. — Surface hairs of U. purpurea; a, sickle-shaped, glandular (muci- 

 lage) hairs; 6, c, young stage of oil-bearing hairs; d-g, mature stage 

 of same, showing oil deposit held by the raised cuticle. 

 Fig. 7. — Glandular hairs of the central boss of the door of U. purpurea, 



shown in developmental stages, numbered serially. 

 Fig. 8. — Diagram of wall structure, showing the inner quadrifid {left) 

 and the outer spherical glands. Vascular tissue between the two 

 cell courses. 

 Fig. 9. — Peltate leaves of U. sp. aff. peltata (from Angola). They bear a 



deep coating of mucilage on their upper surfaces. 

 Fig. 10. — Mucilage glands of the same with their heavy loads of stiff mu- 

 cilage {b)\ c, scheme of branching: a, leaf, with three branches 

 (stolons of second order) emerging from the primary stolon seen 

 axially. 

 Fig. II. — U. gibba, schematized to show relation of door and threshold 

 in the wide-angle type of entrance (cf. 30 — 3). The angular rela- 

 tion of the door posture {p-d) to the general level of the threshold {p- 

 t) is ca. 90 ; r, relaxed posture of door; s, set posture; pr, various 

 possible directions of impact of prey on the tripping bristles; uh, 

 upper hinge; ch, central hinge; Ih, lateral hinge; <j, middle piece. 

 Fig. 12. — Narrow angle door: its shape and areas {cj. jo — 4) and, 

 below, the areas of the threshold, of U. capensis; uh, upper, and Ih, 

 lateral hinge; ma, middle area; mp. middle piece; oz, outer zone of 

 pavement; tnz, middle zone; and iz, inner zone, of same. 

 Fig. 13. — Wide angle door {U. gibba or vulgaris etc.); ch, central hinge. 



