No. 401.] MORTH-AMERICAN INVERTEBRATES. 423 
W 
. Frontal border of cephalothorax with long teeth, only two long spines 
on upper inner edge of tibia of palpus 
Acanthophrynus coronatus Butl. (Cal.) 
Frontal border of cephalothorax only denticulate, more than two long 
spines on upper inner edge of tibia of palpus, smaller species 4 
> 
Between the two longest a of tibia of palpus there are two small 
Admetus fuscimanus Koch (Fla.) 
spines 
Between the two diy en spines of tibia of palpus is only one short spine 
Admetus whitei Gerv. (Tex.) 
SCORPIONIDA. 
The scorpions are readily known from all other arachnids 
by the presence of two peculiar characters; the body termi- 
Fic 2. — Centrurus. a, cephalothorax ; 
* abdomen; c, cauda; d, telson; e, 
ads f, palpus ; 4, hand ; /, fingers; 
orsal area; d.k., dorsal keel; 
LA. Mni keel. 
nates in a poison sting, and on the 
venter, near base of abdomen, is a 
pair of appendages, each bearing a 
number of lamella; these are the 
pectines, or combs. The palpi are . 
enlarged at tip and chelate; the 
claw being of three parts, vzz., 
the hand, or basal portion, and 
two fingers, one movable, the other 
fixed. There are usually three 
groups of eyes. The last five 
segments of the body are much 
narrower than the others and form 
the cauda or tail. These segments 
bear ridges which are called 
“keels.” The legs have no pa- 
Fic. 3. — The two forms of sterna in scorpions. s, 
sternum; £.7., genital plate ; 7, jugum. 
