48 
Psyche 
[Vol. 89 
the mesh is a cone-shaped, rudimentary orb with no sticky spiral. 
The Robinsons attributed a defensive function to these structures, 
and indeed the arguments developed here suggest that barrier 
meshes made by a number of other araneids ( Metepeira , Leucauge, 
Argiope, Arachnura, Gasteracantha, and Phonognatho) may also 
function defensively. 
The evolutionary origin of the orb-plus-cone web designs in 
uloborids is not clear. At least two other uloborid orb-plus-cone 
webs are known. Workman (1896) described the orb-plus-cone web 
of Uloborus quadrituberculatus (Thorell). His apparently schematic 
drawing shows a horizontal orb lacking spiral lines and a cone with 
a 14 loop spiral (he did not note whether or not the spiral was 
sticky). The cone is attached on all sides to surrounding vegetation 
by short lines. In Sembrong Jungle near Layang-Layang, Johore, 
Malaya, Frances Murphy photographed the orb-plus-cone web of a 
specimen matching Workman’s (1896) description of U. quadri- 
tuberculatus. This web was constructed about 1.5 m above the 
ground and had a zigzag outer loop and an irregular cone spiral. An 
unidentified species of Tangaroa collected in mesophyll rainforest in 
the Iron Range, northeastern Queensland, Australia had an orb-plus 
cone web with a zigzag outer loop of rim sticky spiral (V. Todd 
Davies, personal communication). It is not known if the cone spiral 
was sticky. However, a small, unidentified Tangaroa species from 
Yap, Caroline Islands constructed a horizontal orb-web in both the 
field and lab (Joseph Beatty and James Berry, personal communica- 
tion and BDO unpublished observations, respectively), indicating 
that the cone-web is not characteristic of all members of this most 
primitive uloborid genus (Opell, 1979) and, therefore, does not 
represent the “original” uloborid web design. 
We do not know if the cones of the five species studied here are 
constructed in the same manner. Certain behaviors associated with 
cone construction in U. conus (and probably U. albolineatus and U. 
bispiralis ) including the laying of a jagged sticky spiral with few 
attachments to the radii, formation of a cone by cutting and 
reattaching radii to a central line, replacement and reposition of 
radii, and pulling the orb into a cone, have not been seen in other 
uloborids. When one takes into account the webs of other uloborids 
such as Philoponella vicina (Peters 1953, 1955), P. semiplumosa 
(Lahmann and Eberhard 1979), P. oweni (Eberhard 1969), P. divisa 
(Opell 1979), and P. para (Eberhard, unpub.) which are more or less 
