262 Annals Entomological Society of America  [Vol. XIV, 
Among the aquatic Hemiptera, the death feint may have arisen out 
of positively thigmotactic propensities which are manifested to such a 
marked degree by various members of the families Belostomidze and 
Nepide. In a previous paper, attention has already been called to the 
fact that Belostoma and Nepa as well as other closely related aquatic 
Hemiptera cluster together to form groups whenever possible, which 
probably is a manifestation of their positively thigmotactic response. 
Belostoma will crawl, whenever possible, beneath aquatic plants or other 
objects and will then often assume that death-feigning attitude in which 
the legs are folded against the ventral surface of the body. Specimens, 
which had cuddled within thick masses of Elodea or Ceratophyllum, 
often required a considerable amount of shaking to bring them out of 
their inert state. Mepa can be caused to feign while in water by a mere 
contact stimulus. 
The death-feigning response is a common phase of behavior 
among certain Crustacea, especially among members of the 
order Amphipoda, of the family Orchestiide. Holmes (1903) 
discovered that both Talorchestia longicornis and Orchestia 
agilis exhibit this response, the latter in a lesser degree. He 
(1908, pp. 192-193) draws attention to the fact that, in the case 
of Talorchestia longicornis, contact with the fingers and with 
solid objects such as sand and small stones induce the death- 
feint. When the bodies of these animals are surrounded with 
the objects mentioned, thus giving greater contact, the duration 
of the response is much longer than that of individuals lying on a 
flat surface. As members of this species arouse from the death- 
feint, pressure or contact cause them to resume death-feigning. 
Regarding Orchestia agilis, this observer (1903, pp. 194, 195) 
states that contact stimuli exercise ‘‘a sort of hypnotic effect’”’ 
on it. On the other hand, contact may arouse the animal from 
this condition. The thigmotactic responses of Orchestia agilis 
do not appear to be so definitely of the death-feigning character 
as do those of Talorchestia longicornis. 
The entire paper of Holmes (1903) is of an extremely 
important character. His discussion of the probable method 
of evolution of the death-feigning instinct and of its probable 
origin are both very suggestive. He (1903, p. 195) refers to 
another species of amphipod, Orchestia palustris, of the family 
Orchestide, pointing out that, although it responds definitely 
to contact stimuli and lies very quiet when in contact with 
and between solid objects and is aroused with difficulty from 
“its thigmotactic lethargy,’’ yet its response with the death- 
