26 o 
bulletin of the bureau of fisheries. 
between the first and third segments. The principal spur at the fourth stage (fig. 8, ri) 
is still to be seen in its rudimentary state in the adult lobster immediately in front 
of the large functional spurs already described. (PI. xxxvii, fig. i, rud.) 
THE TOOTHED CLAW OR LOCK FORCEPS AND ITS PERIODIC TEETH. 
If the armature of the smaller claw is closely examined, the teeth or spines are 
seen to be arranged in periodic sequence, a fact first noticed by the German naturalist, 
Stahr (257). Stahr’s description is correct, 
so far as it goes, but we can not adopt his 
remarkable conclusions that this should be 
called the “ ornamental ” or “beauty claw,” 
and that the aesthetic sense of this self- 
admiring crustacean is aroused as its eye 
wanders over the dentate margin of its 
“hand.” We should fail, however, to do 
justice to the imagination of this writer 
without quoting directly from his work, in 
which he concludes “That it is not a far- 
fetched idea to recognize in the periodic 
teeth or rows of points of the ornamental 
and sensory forceps an embellishment — an 
architectural and artistic ornament. We 
may mention their close relation to music, 
poetry, and dancing, where we have to 
do with rhythm, time, measure, composi- 
tion, everywhere with periodic sequences. 
* * * Thus it is only natural to sup- 
pose that the beauty sense of a crustacean 
would receive an agreeable impression as 
its eye wanders over the periodic points of 
its claw.” “ 
We have worked out the history of de- 
velopment of both types of claw, in the light 
of which their peculiar structure becomes 
more intelligible. The arrangement of the 
teeth or spines on the smaller claw may be 
expressed by a diagram (fig. ii), in which 
they appear as a linear series, made up 
typically of periods of eight. In respect to size and age, or order of development, 
the eight teeth of each period are symmetrically distributed and fall into four orders 
or series, of which the first and second contain one each, the third two, and the 
fourth four. On this basis the formula for each perfect period or sequence would 
below, showing future breaking joint free at surface, before 
complete fusion has occurred, a temporary interlock at this 
stage by spurs (i* and rp of the second and third podo- 
meres, as well as rudiments of the spurs (s^ and of the 
first and third segments, which form the permanent interlock 
of the adult limb. Compare with figure 13. Swimming 
branch or exopodite (,Ex) functional up to this stage is re- 
duced to a rudiment. Gill filaments (<7. fil) are developed as 
secondary outgrowths of the primary filament, which is a 
fold of the body wall. 
