REPORT ON THE CRUSTACEA MACRUKA. 



555 



The only distinction that I can determine is that in the Challenger specimen, the 

 dactylos of the great chela terminates in a long, slightly curved, tooth-like projection, 

 attached not at the apex but on the under surface near the margin. It may be that it 

 gets worn off by use, or it may have been so hidden in Heller's specimen by the hirsute 

 margin that it escaped notice, as it did in this specimen for some time. 



Alpheus lasvis, Randall (PI. XCIX. fig. 3). 



Alpheus Ixvis, Randall, Journ. Acad. Nat. Sci. Philad., vol. viii. p. 141. 

 „ „ Dana, U.S. Explor. Exped., Crust., p. 556, pi. xxxv. fig. 8. 



„ ,, Heller, Reise der Novara, Crust., p. 107. 



Rostrum spiniform, reaching to nearly the extremity of the first joint of the 

 peduncle of the first pair of antenna?, and separated from the orbital lobes by a deep 

 fissure on each side. Orbital lobes prominent and armed with a small tooth on the 

 frontal maroin. 



O 



First pah' of antennas furnished with a stylocerite that reaches beyond the extremity 

 of the first joint of the peduncle, and to nearly the middle of the second; second joint 

 scarcely longer than the first, third shorter than the second. The flagella are short, the 

 upper being about the length of the peduncle, and the lower about twice the length of 

 the upper. 



Second pair of antennae having the tooth at the base moderately long, and the 

 scaphocerite as long as the peduncle of the first pair, but scarcely so long as that of the 

 second; the flagellum is about half the length of the animal. 



First pah- of pereiopoda subequal on the two sides, both being smooth and compressed, 

 that on the left side having the dactylos shorter than that on the right, and armed at the 

 dactyloid articulation with two blunt teeth, whereas that on the right has none. Second 

 pair of pereiopoda a little longer than the third, and having the second articulus of the 

 carpos subequal with the first, which is rather the longer. The third and fourth pairs 

 of pereiopoda have the meros broad and long, and the carpos and propodos stout and 

 short, the latter being armed on the posterior margin with short spines. The fifth pair 

 is broken, but from the remnant it appears to be more slender than the preceding. 



Telson slightly tapering, with two spines on the dorsal surface, on each side of the 

 median line ; posterior margin rounded and fringed with long hairs, and armed at the 

 outer angles with a small spine. 



