1970] 
Shear — Stridulation 
183 
from Mazatlan, Sinaloa, Mexico. Differences between the left and 
right chelicerae of these specimens were similar to those illustrated for 
the San Bias specimen (Figs. 1, 2). Two females from Apatzingan, 
Michoacan, and a single female from Mazatlan (American Museum 
of Natural History) were also examined, and found to have the 
stridulating apparatus essentially as described for the males. The 
Michoacan females more closely resembled the male from San 
Marcos, Jalisco, than the Mazatlan specimens. 
Fage (1939) described Musicodamon atlanteus from Morocco, 
which has a similar stridulatory apparatus, though the spines are 
arranged quite differently (Fig. 7). Some mygalomorph spiders 
stridulate, using spines on the inner faces of the chelicerae (Millot, 
p. 610 ). 
The stridulating apparatus is absent or replaced by a group of 
much weaker spines in the following species that were readily avail- 
able for examination: Phrynus operculatus Pocock, Tarantula 
palmata barbadensis Pocock, T. fuscimana (C. L. Koch), T. margi- 
nemaculata (C. L. Koch), Phrynichus bacillifer (Gerstaecker) and 
Hemiphrynus raptor Pocock. I also examined a few specimens of 
undetermined species from India, Ceylon, Africa, South America 
and Indonesia, and failed to find any anatomical evidence for stridu- 
lating abilities. Fage (1939) stated that he examined material of 
all species in the very complete collection of the Paris Museum and 
was unable to find evidence of a stridulating apparatus on any species 
except M. atlanteus. Thus it appears that Acanthophrynus coronatus 
is the second example to be discovered of a stridulating whip-scorpion. 
Literature Cited 
Face, L. 
1939. Sur une phryne du sud Marocain porvue d’un appareil stridulant, 
Musicodamon atlanteus, n. gen., n. sp. Bull. Soc. Zool. France 
64: 100-114. 
Millot, J. 
1949. Ordre des Araneides in P. Grasse, Ed., Traite de Zoologie, 
vol. 6 . 
