i6o Natural History Bulletin. 



inch lon^. In each case it is strongly serrated on its upper 

 edge. The antenna? are enormously lengthened, projecting 

 fully nine inches beyond the end of the rostrum and nearly a 

 foot beyond the eyes. The walking legs are also greatly 

 elongated, and are furnished with tufts of hair which are said 

 to aid the animal in resting on the soft bottom. This species- 

 may be identical with jyematocarcimis cnsifcnis, but our 

 specimens came from much shallower water than those secured 

 by the "Blake," which were found in from eight hundred to 

 fourteen hundred fathoms. Ours were taken from one hun- 

 dred to one hundred and twenty fathoms. 



Quite a number of specimens of the genus AlpJicits were 

 secured, belonging apparently to more than one species. 

 Most of them were dredged from a depth of oyer one 

 hundred fathoms, although all the specimens secured by the- 

 ''Challenger" came from depths of less than sixty fathoms.. 

 On a preyious page I was unable to explain the clicking noise 

 made by the large chelae of these animals. Since that passage- 

 was in print, howeyer, I find that Professor W. K. Brooks, 

 offers the following explanation: '-The claw or dactyl is pro- 

 yided with a plug which fits into a well or socket in the other 

 joint, and probably seryes to prevent dislocation. When the 

 forceps are opened the dactyl is raised so that the plug just 

 rests in the mouth of the socket. As soon as the claw is re- 

 leased it is suddenly and violently closed, as if by a spring, and 

 the solid, bony points striking together produce a sharp metal- 

 lic report something like the click of a water-hammer, and so> 

 much like the noise of breaking glass that I have often, when; 

 awal^ned at night by the click of a little Alpheus less than an 

 inch long, hastened down to the laboratory in the fear that a 

 large aquarium had been broken.*'^ In speaking of their pug- 

 nacious habits, the same writer says: '-Watching its oppor- 

 tunity, it springs suddenly upon its enemy, instantly closing its. 

 claw with a violent snap and a loud report, and cutting a ver- 

 tical sweep with its sharp edge. I have often seen Alpheits 



1 The Embryology and Metamorphosis of the Macroura, ^^'. K. Brooks, 

 and F. II. Ilerrick, page 329. 



