550 



THE VOYAGE OF H.M.S. CHALLENGER. 



The second pair of gnathopoda is slender and short, not reaching beyond the 

 extremity of the peduncle of the second pair of antennae. 



The first pair of pereiopoda has the large chela on the right side in our solitary 

 specimen ; it is about as long as the carapace and about three times as long as broad ; 

 the upper surface has a slight depression behind the dactyloid articulation on the 

 inner, outer and inferior surfaces, and is continued longitudinally backwards near 

 the middle of the outer surface, where it gradually dies out. The smaller chela is 

 wanting. The second pair has the two first articuli of the carpos subequal and together 

 longer than the three succeeding. The following pairs have the dactylos long and single- 

 jointed. 



Telson broad, slightly tapering, terminal margin rounded, having a small spine at 

 each angle, and the margin fringed with hairs ; dorsal surface armed with two small 

 spines on each side. 



Length, entire, 



,, of carapace, 

 Depth of carapace, 

 Length of pleon, 

 „ of large chela, 

 „ of dactylos, 



Habitat. — Station 203, October 31, 1874; lat. 11 

 off Panay, Phdippine Islands ; depth, 20 fathoms ; bottom, mud 

 female, laden with ova. Trawled. 



Observations. — This specimen corresponds very closely with Dana's figure and 

 description of Alpheus leviusculus, but differs in having the great chela somewhat 

 narrower in proportion (figs. Ik, Ik"), and the depression on the propodos behind the 

 dactyloid articulation is less decided. In the second pair of pereiopoda the articuli 

 also vary a little, the second articulus being nearly as long as the first, whereas Dana 

 says that " the first is hardly as long as the second, and thin," although his figure does 

 not show such decided variation. His specimen was taken off Wakes Island in the 

 North Pacific, and ours at the Philippine Islands. I therefore consider this specimen 

 to be only a variety of Dana's species, and retain for it the same name as that 

 proposed by the distinguished American carcinologist. He, however, considers his 

 species as being only a variety of the specimens of Alpheus edwardsii which he took 

 off the Cape Verde Islands in the Atlantic. He also says — "It is near the A. 2-incisus 

 of de Haan, which de Haan considers a variety of A. avarus of Fabricius." Dana 

 also remarks that " the large hand is proportionately narrower, but this is often a 

 varying character in the same species." 



