36 THE APODID^ part i 



suspect the presence of a rudimentary antennal gland. 

 No such gland, however, could be found, although the 

 indentation may mark the spot where one formerly 

 opened. Whether this indentation, which was very 

 distinct in some specimens, really represents the 

 remains of an opening of an antennal gland or not, 

 we are still able to assume that such a gland, 

 homologous with the acicular gland of the dorsal 

 parapodium, once existed, and has reappeared in 

 the higher Crustacea as the antennal gland. We 

 have, in the Crustacean head three glands derived 

 from three setiparous glands, viz. the gland of the 

 first antenna (i*) developed into a salivary gland (in 

 Apus), the gland of the second antenna into the well- 

 known antennal gland, and the gland of the second 

 maxilla into the shell gland. The homologous 

 setiparous glands of the mandibles and first maxillae 

 have quite disappeared, like the parapodia to which 

 they belonged. To these points, however, we shall 

 again refer. 



We have given in the Figure (7 B) our explanation 

 of the parts of the second antenna. The correctness 

 of this explanation naturally depends on a right 

 understanding of the same limb in the Nauplius. This 

 matter will therefore be further discussed in the section 

 dealing with the development of Apus. We may here 

 anticipate our conclusion by saying that, in accordance 

 with the homologies given on p. 32, and indicated in 

 the lettering of Fig. 7 B.^ the biramose limb of the 

 Nauplius consists of the dorsal parapodium, the distal 

 portion of which forms the endopodite, the sensory 



