. Natural history of the American Decapoda (Crustacea); Lobster fisheries. 264 BULLETIN OF THE BUREAU OP FISHERIES. The toothed claw, as already remarked, is richly supplied with tufts of sensory hairs above and below the line of teeth and also along the margin of the claw near its tip. These are specially abundant on the underside, and with them the animal is constantly feeling the bottom when it assumes the common alert attitude with the tips of the claws bent down. These tactile setae are arranged in bundles of 200 to 300 or more short, stiff bristles which, like little scrub- V
. Natural history of the American Decapoda (Crustacea); Lobster fisheries. 264 BULLETIN OF THE BUREAU OP FISHERIES. The toothed claw, as already remarked, is richly supplied with tufts of sensory hairs above and below the line of teeth and also along the margin of the claw near its tip. These are specially abundant on the underside, and with them the animal is constantly feeling the bottom when it assumes the common alert attitude with the tips of the claws bent down. These tactile setae are arranged in bundles of 200 to 300 or more short, stiff bristles which, like little scrub- V J ( .,,K 1 1 T T IV m M bing brushes, project from de- pressions in the shell. The floor of each depression is a sieve plate, the perforations of which correspond to the num- FlG. 12.—Projection of serial teeth in segment of big claw of large adult lobster represented in figure 13, showing alignment to lower or ventral {y), originally the anterior, side, the position of the/i^, spur (Si^), and the large displaced lock spine (Z.), the two last serving as guide posts for identification of the periods i-iv. In this and following figures the periods are enumerated from the distal to the proximal end of the claw. ber of setae as well as to the number of nerve fibers supply- ing the bundle. In the adoles- cent stage, when the lobster has attained a length of 3 or 4 inches, the setae of the lock forceps become large matted tufts which sometimes com- pletely conceal the teeth. (Compare fig. 15 and 16). THE CRACKER OR CRUSHING CLAW. In place of tooth-like spines the great crushing claw presents a number of rounded tubercles, both large and small, single or double, and arranged in a characteristic manner (fig. 2 and 3, pi. xLiii). These crushing tubercles are very dense, and in old hard-shell uh (ridge). Fig. 13.—Large segment of right toothed claw from above, to show the periodic teeth; compare projection in figiu-e \2\ uh (ridge), upper ridge of sliding lock joint. lobsters th
Size: 2484px × 1006px
Photo credit: © Central Historic Books / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, bookpublisherwashingtongovtprin
