Cuticle thickness at the point of failure was measured by orienting the fracture surface of the broken pollex towards the viewer so that the line of sight was parallel to the occlusal surface of the pollex (line u, [ILLUSTRATION FOR FIGURE 1 OMITTED]).
c = distance from the neutral axis of the pollex to the upper surface (H/2, where H = height of the pollex parallel to the load vector immediately below the point of crack initiation, in mm: [ILLUSTRATION FOR FIGURE 1 OMITTED]).
I was computed separately for the upper ([I.sub.u]) and lower ([I.sub.l]) half of the cross section of the pollex because the upper cuticle margin was roughly twice as thick as that of the sides or bottom.
Ultimate stress ([[Sigma].sub.b]) could not be computed for all claws for which we obtained safety factors because a few claws broke at the base of the pollex adjacent to the opening where the dactyl inserted, so dimension (f) could not be measured.
McGaughran, "A second case of severe mental retardation and absent nails of hallux and pollex
(Temple-Baraitser syndrome)," American Journal of Medical Genetics, Part A, vol.
short, stout, hooked at tip; a large ridge-like tooth occupying entire central portion; a deep notch at gape.
There were two thick nerve bundles in the intact propodus of the second cheliped [ILLUSTRATION FOR FIGURE 6A OMITTED]: one ran toward its dactyl along the boundary between the opener and closer muscles; the other ran to its pollex along the closer muscle.
In the propodus it was observed that one nerve trunk runs in the direction of the pollex and another to the dactyl.
Kao and Chang (1996) proved that dactyl, pollex, and ischium tissues of the crab claw all had claw-transforming activity if they were auto-transplanted into the autotomized stump of the fourth walking leg.
To examine the regenerative ability of different claw segments, single claw digits (dactyl or pollex), both claw digits (dactyl and pollex), or proximal segments of the claw (ischium + merus/carpus joint) were autotransplanted into eye sockets.
Thus, the coxa and ischium are proximal segments of the claw; the dactyl and pollex are the distal "digits" of a claw.
Table I Summary of limb tissue autotransplantation in the eye socket of Cancer gracilis (carapace width = 12.05 [+ or -] 3.40 mm) (*) Type of regenerate Trials Survival Donor tissue Host eye (No.) (No.) Limblike Limb Claw dactyl ipsi 15 6 0 0 dactyl contra 17 8 1 0 pollex ipsi 15 8 2 0 pollex contra 10 3 1 0 dactyl + pollex ipsi 19 13 2 2 dactyl + pollex contra 23 15 1 1 frozen dactyl + pollex ipsi 12 9 0 0 dactyl + pollex + ischium contra 20 15 1 3 ischium + joint ipsi 23 14 1 1 ischium + joint contra 13 10 1 2 Walking leg dactyl + ischium + joint contra 19 12 3 1 Sham operation ipsi 25 18 0 0 Total 211 131 13 10 * Limblike: a structure that resembles a claw or walking leg and in which handedness cannot be recognized; limb: a claw or walking leg in which handedness can be recognized.