520 
MR. n. N. RIDLEY ON THE 
Antennal scale and peduncle as long as each other, and slightly 
longer than the antennular peduncle. Basal segment of antenna 
furnished below with a strong sharp spine. 
First pair of legs very unequal in size. Dactylus of larger 
hand closing vertically, its greatest length being more than half 
the length of the superior margin of the manus ; without acces- 
sory teeth. 
Anterior margin of the thumb on the inner side nearly 
vertical, meeting the inclined superior margin at an obtuse 
angle ; less than half the length of the superior margin. Thumb 
on the outer side without a vertical anterior margin, the superior 
margin meeting the inferior at an acute angle and forming the 
tooth. 
Manus smooth, without constrictions or depressions, longer 
than the carapace ; superior and inferior margins nearly parallel. 
Carpus rounded above, not bearing a tooth. Meros three-sided, 
flattened below ; superior margin produced in front into a blunt 
process. 
Smaller manus simple ; dactylus and thumb approximately 
equal in length to each other and to the manus. 
Carpus furnished above on the inner side with a small pro- 
jection. Meros resembling meros of larger limb, except that the 
front process is smaller. 
In second pair of limbs the carpal segments are 1, 2 and 5, 3 
and 4. 
First segment almost as long as the second, third, and fourth 
together. Second segment a little shorter than the third and 
fourth together, these being approximately equal; fifth as long 
as the second. 
Meros and carpus of third and fourth pairs of legs not spined. 
Dactyli of limbs not bifid. 
One specimen. If I am right in referring this species to 
Al. panamensis of Kingsley, with the description of which it 
agrees well, it is of interest to note that it occurs upon the 
eastern and western coasts of America. Mr. Kingsley described 
his specimens from Panama and Acajutla. 
Alpheus obeso-manus, Dana. 
1852. Alpheus obesomanus, Dana, U.S. Expl. E.rped., Crustacea, i. 
p. 547, ph xxxiv. fig. 7* 
Carapace smooth, furnished in front with a short rostrum, 
