26o 



BULLETIN OF THE BUREAU OF FISHERIES. 



between the first and third segments. The principal spur at the fourth stage (fig. 8, s'} 

 is still to be seen in its rudimentary state in the adult lobster immediately in front 

 of the large functional spurs already described. (PI. xxxvn, fig. i , s^ 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- 

 P 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. 11), 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 



a All quotations from foreign languages in this work are freely rendered into English. 



Fig. 8. — Base of right great cheliped of fourth stage lobster from 

 below, showing future breaking joint free at surface, before 

 complete fusion has occurred, a temporary interlock at this 

 stage by spurs (j^ and ^) of the second and third podo- 

 meres, as well as rudiments of the spurs (j^ and s^) of the 

 first and third segments, which form the permanent interlock 

 of the adult limb. Compare with figure 13. Swimming 

 branch or exopodite (£x) ftmctional up to this stage is re- 

 duced to a rudiment. Gill filaments {g. fiV) are developed as 

 secondary outgrowths of the primary filament, which is a 

 fold of the body wall. 



