84 



SCIENCE 



[N. S. Vol. XXVI. Xo. 655 



■With reference to this latter type of sym- 

 metry the following observations serve to 

 emphasize the process of regeneration as a 

 factor in the origin of such abnormal ap- 

 pendages. 



Heretofore, a strong presumption has ex- 

 isted that a crusher claw would not be de- 

 veloped on each of the big chelae, first because, 

 as has already been indicated, the claws of the 

 young lobster are alike and similar to the 

 nipper type, and second, that in the adult 

 lobster, the few cases of symmetrical claws 

 were always of the nipper or embryonic type. 

 Up to 1905 the only case recorded of two 

 crushing claws on a lobster was in a foot-note 

 to Herrick's' description of variations in 

 lobster chelae : " I have heard of a single case 

 reported by a fisherman where similar crush- 

 ing claws were developed on both sides of the 

 body" (p. 143). To Przibram writing in 

 1901° this seemed such an incredible phe- 

 nomenon that in view of the theoretical rea- 

 sons indicated above, he concluded that " Der 

 eine Fall von einer Hautung beiderseitigen " 

 crushing claw " von dem Herrick nur vom 

 Horensagen durch Fischer Kenntnis erhielt, 

 wird wohl in der Eeich der Fischermythen zu 

 verweisen sein" (p. 333)." 



Since the year 1905 three authentic cases of 

 lobsters with two crushing claws have been 

 placed on record. One of these was reported 

 by Dr. W. T. Caiman," of the British Mu- 

 seum. He exhibits the photograph of a 

 lobster {Somarus gammarus, Linn.) " with 

 symmetrically developed chelae" which were 

 both crushers (p. 634). Herrick, '07," ob- 

 serves that " this case is, for the present, 

 essentially unique in the literature of the sub- 



"Loc. cit. (2). 



" Loc. cit., (7). 



" I gladly take this opportunity, however, to 

 correct the impression which might be drawn 

 from this quotation. For Przibram in a recent 

 letter has kindly informed me that he has modified 

 his earlier opinion with regard to this matter as 

 the result of his studies on other Crustacea. See 

 especially page 215 of his monograph on "Die 

 Heterochelie bei deeapoden Crustaceen," Afchw. f. 

 Entw.-Mech., Bd. XIX., 1905. 



"Loc. cit. (1). 



^Loo. cit. (1). 



ject " (p. 277), but in making this statement 

 he has evidently overlooked my description," 

 published in 1906, of the two other lobsters 

 with similar crusher claws. The latter two 

 cases of similar crushers were regeneration 

 products, and they are, as far as I am aware, 

 the only cases on record in which the origin 

 of the two crushing chelae is known, for in 

 neither of the cases recorded by Herrick and 

 Caiman has the history of the abnormal 

 chelffi been obtained. A brief restatement of 

 the facts with regard to these regenerated 

 crushers may, t^herefore, be in place here:** 



One of these cases was obtained in the course 

 of a series of experiments on regeneration made 

 during the summer of 1905, and the other during 

 similar experiments in 1906. In both instances 

 the lobsters had been recently taken from the 

 traps near the experiment station, placed in float- 

 ing cars and kept in as normal a condition as 

 possible. Let us designate the former as specimen 

 A, and the latter as specimen B. 



Specimen A. — The original appendages of this 

 specimen were all normally developed and the 

 animal was in a healthy condition throughout the 

 experiment. The lobster was a female and meas- 

 ured 8^ inches in length. On July 26, 1905, both 

 chelfE, and the second and third right walking legs, 

 were autotomously removed. On September 28, 

 sixty-four days after the amputation, the lobster 

 moulted and then measured Si inches. It had 

 meantime regenerated both chelae, and the second 

 and third right thoracic legs. 



The original left claw of this lobster was a com- 

 pletely developed crusher, characterized by the 

 wide massive claws with an almost entire absence 

 of tactile hairs, and by the presence of broad 

 tubercle-like teeth. The right chela was of a char- 

 acteristic nipper type with a relatively slender 

 claw, pointed cutting teeth, and a fringe of tactile 

 hairs along the jaws. The right and left clielse 

 measured 146 and 140 mm. in length, respectively. 



Soon after the amputation of these limbs an- 

 other pair of chelfe began to regenerate from the 

 remaining stump or basipodite. July 18, twenty- 

 three days after the amputation, the regenerating 

 buds both measured 5 mm. in length. By the time 



"Emmel, V. E., 1906, "The Regeneration of 

 Two Crusher-Claws following the amputation of 

 the Normal Asymmetrical Chelse of the Lobster," 

 Archiv. f. Enttv.-ilech., Bd. XXII. 



" For a more detailed description with figures, 

 see loc. cit. (3), (13). 



