Hawaiian Crangonidae — BANNER 
107 
that were definitely C. brevipes did reach the 
minimal ratio of 1.4. Therefore, it is likely 
that, if enough specimens were measured, the 
edges of the normal distributional curve would 
overlap. Another graph, not reproduced here, 
was made to ascertain whether the ratio be- 
tween the articles varied with the size of the 
specimens; in this the ratio of the lengths of 
the first two carpal articles was plotted against 
the length of the carapace. This study showed 
no correlation whatsoever, with both species 
having great variation in ratios for all size 
ranges. 
On the basis of these four variable charac- 
teristics, satisfactory separations of the two 
species may be made. If, for example, the ratio 
of the first two articles of the carpus of the 
second legs was between 1.3 and 1.5, in cases 
where it was undecisive, then the specimen 
could be assigned to its correct species on the 
basis of the teeth of the merus of the large 
chela or of the basicerite. In none of the well 
over 200 specimens examined was any doubt 
encountered as to the identity of an individual 
specimen. 
The belief that these are indeed separate 
species is confirmed by the study of paired 
specimens. Both of these species live in algae- 
covered tubes on old coral; in each tube there 
is a single pair of specimens, a male and a 
somewhat larger female which are evidently 
mates. During routine collecting, whenever it 
was possible to get both members of this pair, 
they were removed and preserved for special 
study. In the small number of these pairs 
available, none consisted of mixed species— 
either both were plainly C. brevipes or both 
were plainly C. clypeata. 
This endemic species apparently has been 
derived from the Indo-Pacific C. clypeata. As 
the differences between the species are neither 
constant nor of great magnitude, as the hab- 
itat remains the same, the separation of the 
two species can be presumed to have been in 
relatively recent time. 
Coutiere described a species, C. parabrevipes 
(1898^: 151), which he thought might be iden- 
tical with this species. It was plainly a differ- 
ent species as C parabrevipes had grooves and 
ridges on its chela which are entirely lacking 
in C. brevipes. C. parabrevipes (Coutiere) was 
considered a synonym of C. acuto-femorata 
(Dana) by de Man (1911). 
DISTRIBUTION: The species appears to be 
moderately plentiful on Oahu, where it was 
collected both in shallow water of the reef flat 
and outside the reefs in water to about 20 feet 
deep at the following locations: off Mokulua 
Islands, Waimanalo, Hanauma Bay, Waikiki, 
Nanakuli, Mokuleia, Kawela Bay. It was col- 
lected at Halape, Kau Coast, Hawaii, by R. 
W. Hiatt, in coral at a depth of 30-40 feet. 
The only record of the species from deep water 
is two specimens collected in 30 fathoms off 
Waikiki Beach. 
Crangon clypeata (Coutiere) 
Figs. 37, 38 a-k, 39 a-u 
Alpheus clypeatus Coutiere, Fauna and Geog. 
Maid, and Laccad. 2: 897-898, pis. 81-82, 
figs. 36-36g, 1905. 
DESCRIPTION: Frontal border, seen from 
above, truncate and projecting, with margin 
from slightly concave to slightly convex. Ros- 
trum either small or lacking. Dorsal carina 
high and definite, sharp or rounded, anteriorly 
terminated abruptly before reaching edge of 
frontal area. Area between orbital hoods and 
■Ratio of second to first article 
of carpus of second legs 
Fig. 37. Comparison of carpal ratio of Crangon cly- 
peata (Coutiere) and Crangon brevipes (Stimpson). 
