150 



MERISTIC VARIATION. 



[part I. 



limbs of the two sides ; that the exopodite of the right side is 



B 



Fig. 18. Cancer pagurus <? ; the right and left third maxillipedes, that of the 

 right side having the endopodite in the likeness of the endopodite of a chela. 

 bp. basipodite, cp. carpopodite, dp. dactylopodite, ep. epipodite, g. groove between 

 parts representing ischiopodite and meropodite, g'. groove representing the suture 

 at which a normal chela is thrown off if injured. From P. Z. S., 1890. 



essentially like that of the left, but that it lacks the inner process 

 and the flagellum which are borne by the normal part. There was 

 some indication that this branch of the limb had been injured, and 

 perhaps the flagellum may have been torn away, but the appear- 

 ances were not such as to warrant a conclusion on this point. The 

 branchial epipodites (not shewn in the figures) were normal in 

 both cases. The endopodite of the right side was entirely peculiar, 

 and was, in fact, literally transmuted into the likeness of one of 

 the great chelae. It consists of a single joint (mi), articulating 

 with the basipodite centrally and bearing the carpopodite. This 

 single joint represents, as it were, the ischiopodite and meropodite 

 of an ordinary chela, but these two parts are ankylosed together 

 and the articulation between them is only represented by a groove 

 (g). Another groove (g') represents the groove upon the ischiopo- 

 dite of the chela, at which the limb is commonly thrown off by 

 the animal if it is injured. The carpopodite, propodite and dactylo- 

 podite are freely moveable on each other and hardly differ, save 

 in absolute size, from those of the normal chelae. The shape, pro- 

 portions and texture are all those of the chela. Bateson, W., 

 Proc. Zool. Soc, 1890, p. 580, fig. 1. 

 80. A similar case 1 of Cancer pagurus % . 4 inches across carapace, 

 mature, right pedipalp [i.e. 3rd maxillipede] normal, left pedipalp 

 modified into a chela having all the joints clearly defined, Cornish, 

 T., Zoologist, S. 3, VIII. p. 349. 



*81. Palinurus penicillatus. The left eye bearing an antenna- 

 like flagellum, growing up from the surface of the eye as shewn 

 in the figure (Fig. 19). The eye-stalk and cornea, as represented, 

 appear to have been of the normal shape but reduced in size. 



1 Similar cases since published by Richard, Ann. Sci. Nat., Zool., 1893. 



