WILLIAMS: HABITS OF SCUTIGERELLA. 
467 
Ac ARINA. 
Unidentified but abundant. A young tick of an undetermined species was 
found on a Scutigerella. 
Pseudoscorpionidae, possibly Atemnus elongatus Banks. 
Mollusca (kindly identified through Mr. C. C. Adams). 
Bifidaria armingeria Say. 
Bifidaria pentodon Say. 
Polygyra sp. 
A species of Ponerine ant is fairly common in the Scutigerella 
habitat. It is probably Ponera coarctata. 
The spiders, flies, beetles, and ants are all unworked and those who 
are familiar with faunal lists from similar habitats perceive that this 
list is far from complete. Enough, however, is given to show some¬ 
thing of the character of the fauna. 
Light and Water Relations. 
Scutigerella is a cave animal as is seen by its white color and the 
slight development of eyes. According to Grassi ( 86) they prefer 
rocky soil in the shaded regions for their habitations and where there 
are no stones the animals are not to be found. Williams (’ 04 ) reported 
that they are to be found isolated beneath flat stones in the drier 
portions of a stream bed and in a restricted area along the body of the 
stream. 
Neither of these authors is absolufely correct. During parts of the 
year here in Ohio at least, the Scutigerellas are to be found in the 
spaces between the decaying leaves of the forest floor, quite far from 
either soil or stones. Moist wood that is sufficiently decayed to be 
burrowed in by insects is likely to contain them in its passageways. 
The chief factors determining their distribution seem to be an at¬ 
mosphere of great humidity, a moderate temperature, comparative 
darkness, and an undisturbed — at least uncultivated — soil. 
In April, when Scutigerella is fairly abundant, the temperature 
of the air is low and it is usually well laden with moisture. Several 
experiments with a wet-bulb thermometer indicated a relative humidity 
of the air above the ground of 60%. In the leaves on the ground 
where the animals were found, water always deposited at once on the 
sides of the glass vessel in which the captured animals were placed 
indicating a still higher relative humidity of the atmosphere, essentially 
saturation. 
