142 
d 
PACIFIC SCIENCE, VoL XIII, April, 1959 
LOCALITIES: 2 specimens, Midway Island, 
Hawaiian Archipelago; collected by Y. D. P. 
Speicer, 1941. Six specimens, Ahoolaka (”Sand 
Island”), Kaneohe Bay, Oahu, Hawaiian 
Archipelago, under coral heads; collected by 
A. H. Banner, August, 1955. 
DISCUSSION: In the group of specimens 
from Kaneohe Bay listed above an interesting 
variation occurs in the dactyli of the third, and 
to a lesser extent, the fourth legs. In most of 
the specimens from Hawaii these dactyli are 
either simple like the neotype (Banner, 1953, 
fig. 43j) or with a very small thickening or 
shoulder similar to those shown in Figure 
7c, d. However, in this group of specimens 
from Kaneohe Bay, three specimens, male 
and female, have a definite and well-developed 
secondary unguis (Fig. 7a)\ the other speci- 
mens from the same locality had the second- 
ary unguis developed as a shoulder only 
(Fig. lb). There are no other noteworthy 
variations in either group of specimens. In 
the whole series of specimens it is the third 
legs that have the greatest development of 
the secondary unguis, and usually the fourth 
have but a slight thickening at most; more- 
over, often the accessory tooth or shoulder is 
not of uniform bilateral development. 
The extensive collections of this species 
from the central Pacific area were spot 
checked for this characteristic, and it was 
found that most specimens were of inter- 
mediate development, similar to the condi- 
tions shown in Figure ib-d. The extreme 
development, similar to the conditions shown 
in Figure la and e, were both rare. 
Obviously, no significance should be at- 
tached to this variation. 
An error in the redescription (Banner, 1953: 
119) should be corrected. In describing the 
dactylus of the third legs, the text states: 
"Dactylus simple ... as long as merus.’Hn- 
Fig. 7. Alpheus diadema Dana, variation in the 
dactyli of the third legs, a, Male, 19 mm. long, Kaneohe 
Bay, Hawaii; b, female, 24 mm. long, same locality; 
c, male, 15.5 mm. long, Tutuila, American Samoa; 
d, male, 18 mm. long, Midway Island; e, male, 17 mm. 
long, Tongatabu, Tonga. All drawn to the same scale. 
