SECT, in THE APPENDAGES 49 



in the posterior rowing limbs it is a flat piece forming 

 part of the swimming plate (Fig. 10). What we here 

 call the most distal appendage is, however, according 

 to the homologies described on p. 32, in reality the tip 

 of the dorsal parapodium. 



The exites, or appendages on the back of the limb, 

 are always two in number, the distal being a 

 swimming plate (flabellum, homologous with the 

 sensory cirrus of the Annelidan parapodium), much 

 reduced on the first limb but well developed on all 

 the rest, and the proximal a gill which corresponds 

 in position with the gill on the dorsal parapodium of 

 the Annelid. 



The limbs themselves have been so often described 

 that it is not necessary here to do more than refer to 

 the drawings (Fig. 9, 4, 5, 10). 



Returning now to the homologies here set forth 

 between the Crustacean limbs and the Annelidan 

 parapodia, we find that they differ considerably from 

 those generally put forward. Although as far as I 

 know the point has not been worked out in detail, it 

 is assumed that the exopodite is homologous with the 

 dorsal, and the endopodite with the ventral para- 

 podium. We have here, however, seen that in the 

 typical biramose trunk limb the ventral parapodium 

 has disappeared, perhaps being used up in the forma- 

 tion of the basal joint, and that the limb proper is 

 formed of the dorsal parapodium, the distal end of 

 which forms the endopodite, while its sensory cirrus 

 forms the exopodite. 



Such a result might be expected on theoretical 



E 



