276 BULLETIN OF THE BUREAU OF FISHERIES. 



these writers seems to have found this variation of similar toothed claws much more 

 common in the European lobster." The history of development proves, as Stahr main- 

 tained upon theoretical grounds, that the toothed claw represents the more primitive 

 and the crushing claw the more modified type. Therefore it seemed natural to infer, 

 as he did, that the anomalous symmetry in these weapons had been brought about by 

 loss of a crushing claw and a subsequent reversion to the primitive toothed condition in 

 the regenerated member which took its place. This would give us a lobster with sym- 

 metrical toothed claws Uke the variation described. 



The converse of this, or the production of a new crushing claw in place of a toothed 

 "forceps," could not occur upon Stahr's theory of regeneration, and hence he inferred 

 that my report of a case of similar crushing claws in a lobster was an error. It was 

 later at first rejected on similar grounds also by Przibram, who regarded the report as 

 incredible and "worthy of being consigned to the realm of fishermen's myths." It 

 should be added, however, that this objection was withdrawn in a later contribution 

 {22£), and neither Stahr nor Przibram are to be blamed, for my report was based upon 

 the statement of a fisherman. Still, however great the inaccuracy of fishermen in 

 biological matters, I have yet to find a lobsterman who could not tell a "club" from a 

 "quick" claw. It now seems that the maligned fisherman, for once at least, was right, 

 and he should get his dues even if earUer theories have to be revised, for Dr. W. T. 

 Caiman, of the British Museum, has described a case of symmetrical crushing claws in 

 the European lobster (43), and his account is accompanied by an excellent photograph, 

 which he has kindly permitted me to use (pi. xxix). In all other respects this animal 

 was a perfectly normal male. It was caught near Stromness, Orkney, and its living 

 weight was 4 pounds 10 ounces. 



In a letter, under date of December 3, 1906, regarding this unique specimen. Doctor 

 Caiman says : 



The correspondence between the two chelae as regards arrangement and size of the crushing tubercles 

 is even closer than appears on the photograph, where slight differences of color have a little obscured 

 the shape in one or two points. The differences are no greater than one would expect to find between 

 the two sides of a normally symmetrical animal. In other respects the chelipeds are practically alike 

 in size and shape, except that, as seen on the figure, the dactylus of the left is shorter than that of the 

 right. The basal segments of the limbs show no trace of asymmetry, which is often associated with 

 regeneration. 



To return to Emmel's paper (93), we. find that in two recorded cases, an S^^-inch 

 female and an 8-inch male, "crusher claws" were regenerated after amputation by 

 autotomy of normal asymmetrical chelse. Emmel further records the capture at the 

 Rhode Island experiment station in 1895 of a single adult lobster with similar "nipping" 

 claws. When these were removed by autotomy two similar claws were also reproduced, 

 but in this instance of the "nipping" type, like those cast off. 



While in the usual course of events regeneration of a large cheliped restores the 

 normal asymmetry of an adult lobster, Emmel has clearly established the fact that it 



o Przibram (22j) has reported a case of similar toothed claws in a spedmen of the Norwegian lobster (Nephrops norvegicm) 

 preserved in the Hofmuseuin of Vienna. 



