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PACIFIC SCIENCE, Vol. XIV, April I960 
Fig. 5. Athanas dorsalis (Stimpson), a 5.5 mm. (carapace length) ovigerous female from Raroia, Tuamo- 
tus, Station 1847. a, b, Anterior region, dorsal and lateral aspects; c, d, large and small chelae, lateral view; 
e, f, same, from lower side; g, second leg; h, third leg; i, third leg, dactylus; j, telson and uropod. 
a gradual series from those with pronounced 
teeth to the few with very slight teeth and to the 
one specimen (from the Tuamotus) without 
any teeth. 
Antennular and Antennal Peduncles: Usually 
the stylocerite reaches to near the end of the 
antennular peduncle, the scaphocerite and carpo- 
cerite exceeding the stylocerite slightly; in no 
case are the differences in length pronounced, 
and at times the relationships change. 
Large Chela: This appendage is found to ex- 
hibit strong growth and sexual differences (see 
Fig. 6a— f), with the young of both sexes show- 
ing a more or less uniform taper to the fingers 
which bear minute serrations on the basal two- 
thirds and the distal third being smoothly 
rounded to the curved tip. In adult females there 
is commonly an outgrowth of an irregular lobe 
proximal to the distal curve on the larger chela, 
while the other chela remains more like that 
found in the young. In some of the largest males 
the large chela has developed an exceedingly 
large tooth on the fixed finger, against which 
the dactylus closes; however, in other large 
males and in all smaller males this tooth is 
variously developed and much smaller. In both 
sexes the development of the chelae varies con- 
siderably between individuals of the same size, 
and in one very large ovigerous female the tooth 
of the fixed finger is as fully developed as that 
of the large male. 
Small Chela: In most specimens, male and 
female, the cutting edge of the finger bears nu- 
merous low irregularities which stop abruptly 
in a tooth that may be obtuse or a right angle. 
The distal portion is curved. However, in some 
the irregularities are considerably smoothed, and 
the final tooth may be low and rounded. 
