164 
well with the specimens from Hawaii except 
that the dactylus of the third leg, instead of 
bearing a smooth convexity, carries an ex- 
ceedingly small secondary unguis similar to 
but smaller than that found in C. brachymerus 
Banner (1953: fig. 11]). The external spine 
of the uropod is colorless. 
In considering the specimens from Saipan, 
Amo, and Onotoa, the question arises as to 
the taxonomic level of this form. Obviously 
it is closely related to the A. gracilis of Heller, 
but whether it should be considered as a sep- 
arate species, as a geographical subspecies, or 
as a variant — as it is now described — of the 
basic species, cannot easily be determined. 
On the basis of the Hawaiian specimens alone 
it would appear to be a separate species, or at 
least a subspecies; however, the specimens 
are from wide-spread localities. Yet none of 
these extra-Hawaiian forms are exactly like 
the specimens from Hawaii. It is possible that 
each of the studied archipelagoes have popu- 
lations that could be interpreted as separate 
subspecies; certainly these variations appear 
to validate the consideration of these or the 
Hawaiian form as separate species. Yet the 
samples from the other archipelagoes have not 
been extensive enough to draw any conclu- 
sions about the populations, and many areas 
of the Pacific have not been sampled at all. 
Therefore the form is left as it was described 
originally with a tentative infrasubspecific 
designation. 
Alpheus ventrosus Milne Edw., 1837 
Fig. 4 
For synonymy see Banner, 1956. 
localities: 2 specimens at GOC-22, 1 at 
GOC-33, 2 at GOC-36, 7 at GOC-51. 
discussion: This group of four specimens 
from GOC-51, together with specimens from 
Saipan and Arno, present an almost complete 
intergradation between the small (8.5 mm.) 
form described as A. latipes and A. ventrosus 
which reaches a length of more than 40 mm. 
PACIFIC SCIENCE, Vol. XII, April, 1958 
While A. latipes as described was similar in 
general configuration to A. ventrosus , the two 
were distinctly separated by a number of char- 
acteristics. In the front of the carapace in A. 
latipes , the rostral carina was narrow and sharp 
and the orbital teeth were confluent with the 
front of the carapace, instead of having a 
flattened rostral carina and having the orbital 
teeth demarked medially from the margin of 
the carapace as is a characteristic for A. ven- 
trosus. The antennular peduncles and the sec- 
ond and third legs were relatively broader in 
A. latipes . The fingers of the large chela were 
relatively shorter and the merus of the large 
and small chela were feebly armed or com- 
pletely unarmed in A. latipes , instead of bear- 
ing up to four or five strong spines as in A. 
ventrosus . The dactylus of the third leg was 
abruptly curved and strongly acute in A. 
latipes , while in A. ventrosus the dactylus was 
of a peculiar blunt form, with a growth on the 
tip that was reminiscent of a horse’s hoof. 
(Compare figs. 27, 28, Banner, 1953.) 
Yet this group of specimens, ranging in 
size from 8.2 mm. to the adult size, shows 
an almost perfect intergradation in all of these 
characteristics. Two of the most marked and 
most easily observed characteristics, the form 
of the rostral carina and the form of the dac- 
tylus of the third legs, were chosen for de- 
tailed study and illustration. The four smaller 
specimens came from the station mentioned 
above; the last specimen came from the au- 
thor’s collection from Saipan. 
In the 8.2 mm. specimen, the parts are 
almost identical to those described for A. 
latipes; if anything the dactylus of the third 
leg is slightly thinner. In the 9-7 mm. speci- 
men the rostral carina does not change, but 
the dactylus is developing some extra superior 
and inferior thickenings. In the 10.8 mm. 
specimen the rostral carina still remains con- 
stant, but the dactylus is definitely growing 
thicker, the hook smaller, and a superior and 
inferior ridge is becoming more marked. In 
the 15.4 mm. specimen the interorbital por- 
tion of the rostral carina is broader and flatter, 
