194 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



Smaller hand slightly compressed, as long as larger ; fingers longer than 

 palm, the thumb being longer than the dactylus; both very slender, 

 not completely closing, and fringed with long hairs. Ischium of secoud 

 pair longer than the meros; carpus five-jointed, first joint a little 

 shorter than the second, the last three subequal and together as long as 

 the second. Three posterior pairs without spines on the meral joints; 

 propodi hirsute; dactyli lamellate. Telson tapering, twice as long as 

 broad ; the apex obtusely pointed. 



Length of body. Carapax. Hand. 

 29.5™'" 9.3™™ 15.5"'"^ 



Fort Jefferson, Florida {Lieutenant Jacques, U. 8. N.). 

 Alpheus heterochelis Say. 



Alpheus heterochelis Say, I. c. i. 243. — Edwards, op. eit. 356. — DeKay, op. cit. 26. — 



Gibbes, I. c. 196. — Smith, Trans. Conn. Acad. ii. 23, 39. 

 Alpheus armillatus, Edwards, op. cit. ii. 354. 

 Alpheus lutarius Saussure, Crustacea Nouv. des Antilles et du Mexique, 45, pi. 



iii. f; 24. — V. Martens, Wiegmann's Archiv fiir Naturgeschichte, 1872, 139. 

 Halopsyche lutaria Saussure, Revue Zoologique. 18.57, 100 {teste Saussure). 



Carapax smooth; rostrum short, acute, depressed; ocular arches with- 

 out spines. Basal spine of antennulae stout, short, not reaching base of 

 second joint; second joint more than twice as long as third. Outer 

 flagellum half as long as inner. Antennal scale as long as antennular 

 peduncle, the spine on the anterior lateral margin large, stout, acute ; 

 inner margin arcuate, widening toward the base ; flagellum somewhat 

 longer than the body. Feet of the first pair unequal ; meros joint tri- 

 angular; carpus as broad as long. Larger hand one and a half times 

 as long as carapax, compressed, margins rounded ; a constriction of the 

 upper and under margins at about the middle. Thumb three-fourths as 

 long as i^almar portion, a strong rectangular tooth on inner portion of 

 occludent margin ; apex acute. Dactylus with a process on the inner 

 margin, which shuts into a cavity in the opposing thumb; points of 

 fingers overlapping. The smaller hand cylindrical, the constrictions 

 but faintly indicated ; fingers three-fourths as long as palm. Dactylus 

 flattened; occludent margin with a longitudinal carina, shutting into a 

 groove in the thumb, the fingers with a fringe of hairs. Feet of the sec- 

 ond pair slender, filiform; ischium and meros equal; carpus five-jointed, 

 first joint as long as second and third, second as fourth and fifth, third 

 and fourth equal, fifth a half longer than preceding. Telson subquad- 

 rate; extremity arcuate. 



The variations I have observed from the above description are as fol- 

 lows: — In specimens from Florida, I have found the front threespined, 

 the ocular spines, however, being smaller than the rostrum. In a speci- 

 men from Nassau, N. P., there is a groove upon the upper margin of the 

 propodus of the larger hand, which at about a median point between the 

 base and the articulation of the dactylus bends and is continued for a 



