1921] Schmitt: The Marine Decapod Crustacea of California aur, 
Antenna 
Cy a 
h a ion 
ee gfe Esters! he or (em or ee) gland 
SS 
od oT (meropodite) Ss. 
ce 61 third or outer N 
Pteryaostomian 
PteryaosTomian Y? 
%? region region 
Fig. 7. Ventral view of anterior part of body of a brachyuran decapod. The 
roof of the buccal cavity is known as the endostome or palate. 
Measurements.—Length is always measured on the median line 
from the anterior to the posterior margin. The length of the rostrum 
is measured from the line connecting, in shrimps, the posterior, and 
in crabs the upper margins of the orbits. ‘‘The length of segments 
is measured on the upper or anterior margin. The length of the 
whole cheliped or leg is measured on the lower margin from the 
articulation of the coxa with the sternum to the tip of the dactylus. 
The length of the immovable finger is measured from the tip to the 
extremity of the sinus between the fingers.’’ (Rathbun, 1918, p. 8.) 
Width of carapace, and of segments of the chelipeds and legs is 
measured at the widest part. ‘‘The fronto-orbital width is measured 
from the outer angle of one orbit to the outer angle of the other.”’ 
In erabs ‘‘the width of the rostrum is measured at its posterior end.”’ 
(Op. cit., p. 8:) 
