JOURNAL OF ENTOMOLOGY AND ZOOLOGY 195 
on the dorsum. The appendages are also clothed with similar 
small hollow hairs of the type found so generally among arthro- 
pods. These hairs are very small in many places but in certain 
regions as on the pedipalps they are very long and slender. The 
hairs are not only hollow but there is a passageway through the 
chitin below the seta, even in places where the body-wall is very 
thick. Some hairs are sunken at their bases and the whole 
neighborhood of the seta elevated into a little knob. Sensory 
cells of a bipolar type are found at the bases of the hairs in the 
more perfect sections, these send one process into the base of 
the hair. These cells were often easily distinguished from the 
surrounding hypodermal cells by their different shape and 
staining reactions although the cell process might not extend 
into the hair. It seems probable that all the hairs of the animal 
are sensory and probably tactile. Possibly the long hairs of the 
pedipalps are also tactile. There was no evidence of any other 
sense organ except the eyes. In addition to the usual type of 
hair just described a simple branched form was found. 
There are two simple eyes, one on either side of the head near 
the base of the pedipalps. These eyes consist of a thin layer of 
clear chitin on the outside and a small group of sensory cells 
below this. On the surface of the cornea of chitin a number of 
regular knobs of small size take certain stains such as methylene 
blue. 
Peripheral nerves, such as those supplied to muscles were 
found especially in longitudinal sections of appendages. These 
strands were found to be very delicate and deeply staining 
nuclei were found along the course of the fibers. 
PeERIPHERAL GANGLIA AND Puexuses. No very definite periph- 
eral centers were found in Chelifer, but in certain dissected 
specimens in the head and thoracic region there are individual 
cells and small groups which undoubtedly serve as peripheral 
ganglia. Some of these seem to be quite intimately connected 
with the more cephalic nerves and the central nervous system. 
Some of these seem to be true nervous elements although all may 
not be. Most of the cells and groups of cells are clustered about 
the cephalic portion of the nervous system. The numerous 
