38 
PACIFIC SCIENCE, Voi. VII, January, 1953 
don from the specimens described; in this 
specimen the merus of the third legs was only 
2.5 times as long as broad and the basal por- 
tion of the superor unguis was only slightly 
broadened. This specimen had all the other 
characteristics of the species, including the 
excavated ventral hook of the dactylus, so it 
was assigned to this species. 
These Hawaiian specimens agree well with 
Heller’s original description and with de 
Man’s redescription of the same species from 
the East Indies (de Man, 1911). Heller did 
not remark upon the peculiar superior unguis 
of the dactylus of the third legs, but it was 
described fully by de Man. All differences 
noted were minor ones of proportions, such 
as the length of the stylocerite, which was 
found to be quite variable in the closely re- 
lated S. paraneomeris. 
This species is very similar to S. paraneo- 
meris Coutiere in general body form and pro- 
portion, especially when the variation of S, 
paraneomeris is considered. However, the na- 
ture of the dactyli of the third and fourth legs 
affords a rapid and certain method of distin- 
guishing the two. To separate this species 
from S. prolificus (Bate) see the discussion 
under that species. Ramadan (1938) considers 
S. helleri de Man (1911: 194, 245) to be prob- 
ably a synonym of S. charon, but reaches no 
definite conclusion. 
DISTRIBUTION: This species appears to oc- 
cur almost exclusively in living heads of Pocil- 
lopora meandrina Verrill, which it inhabits 
with Crangon ventrosa (Milne-Edwards) and 
crabs of the genus Trapezia. It therefore could 
be expected from all reefs and other areas 
where this coral grows. It has been collected 
at Mokulua, Waimanalo, Hanauma Bay, 
Black Point, Waikiki, Nanakuli, Mokuleia, 
and Kawela Bay on Oahu, and at Lahaina on 
Maui, in water ranging from a few feet to 
about 20 feet deep. As reported by Coutiere 
(1909), the ''Albatross” collected the species 
at two stations off Laysan in water from 10 to 
30 fathoms deep and off the northeast coast 
of Maui in 13 fathoms (Stations 3962, 3955, 
4073). 
S. charon has been reported from many 
places between the Red Sea and Hawaii, in- 
cluding several localities in the Indian Ocean, 
South China and southern Japan, Australia, 
and Thursday Island in the Pacific. 
Synalpheus prolificus (Bate) 
Pig. 12 a-c 
Alpheus prolificus Bate, Challenger Rpt. 24: 
556-557, pL 99, figs. 4, 4c, 4m, 1888. 
As no specimen of this species was avail- 
able the original description is given: 
Carapace two-thirds the length of the pleon. The 
rostrum narrow. The orbital lobes pointed, broad and 
nearly equal in length to the rostrum. 
First pair of antennae have the second joint of the 
peduncle shorter than the first, the third subequal with 
the second. Stylocerite a little longer than the first joint, 
flagella subequal and about as long as the carapace. 
Second pair of antennae as long as the animal, pe- 
duncle longer than that of the first pair, basal tooth as 
long as the stylocerite and nearly half as long as the 
scaphocerite, which is subequal with the peduncle. 
First pair of pereiopoda lost. Second slender, having 
the carpos five-articulate, the first articlus being longer 
than the four following ones. Third and fourth pairs 
robust, meros broad, compressed, without distal tooth; 
carpos anteriorly produced on the upper distal margin; 
propods curved, furnished with spines on the posterior 
margin; dactylos stout, bluntly pointed, with a small 
secondary unguis on the outer surface (fig. 4m). 
The pleopods are broad and foliaceous. 
Telson broad, smooth, furnished with two spinules 
on the dorsal lateral surface, tapering and rounded at 
the extremity. 
Length, entire 20 mm. (0.8 in.) 
" of carapace 8 
Depth of carapace 5.5 " 
Length of pleon 12 
Habitat~OE Yionolnln, Sandwich Island; depth 18 
fathoms. One specimen; female. 
Observations — This species is one of those that ap- 
proach Alpheus neptunus Dana (PI. Cl, fig. 2) and Al- 
pheus biunguiculatus Stimpson. It differs from the former 
in having the carpos of the third and fourth pairs of 
legs anteriorly produced at the upper distal extremity 
and in having the dactylos biunguiculate, and from the 
latter (PI, Cl, fig. 4) in being generally more robust, in 
having the rostrum and supraorbital teeth less prom- 
inent, the carpos of the third pair of pereiopoda pro- 
duced on the upper margin, and the dactylos short and 
thick, the second unguis being rudimentary and situ- 
ated behind the larger on the outer margin. 
Our specimen is a female and carries a very large 
mass of ova; hence the name. 
