514 



HFNRY M. BFRNARn, 



shown was probably the case in the primitive Crustacea, to, receive 

 the food thus held. All the biting and catching actions were carried 

 on at the anterior end of the body, round an anterior mouth, by means 



St 



Fig. 2. Embryo of Melolontha (after Graber, from Korschelt aud Heider's Lehr- 

 buch der vergleichenden Entwicklungsgeschichte), showing the position and strictly meta- 

 meric arrangement of the stigmata, and the originally metastomial position of the an- 

 tennsp and oral appendages. 



Fig. 3. Embryo of Hydrophilus (after Heider , from Lang's Text-book of Com- 

 parative Anatomy) , showing the position and metameric arrangement of the stigmata. 

 The oral appendages have moved forward to cover the mouth. 



ot the more anterior pairs of parapodia, modified into mandibles 

 and maxilla;, as we shall presently try more minutely to describe. Thus, 

 in the Tracheatan-Annelid, the ventral parapodia along the trunk would 

 naturally be used as limbs , to be developed later into the variously 

 formed ambulatory legs. The dorsal parapodia, on the other hand, 

 would disappear. 



We assume, then, that when the dorsal parapodium itself disap- 

 peared its acicular gland persisted, modified for new functions, viz., in 

 the present case, to form the tracheœ of the Hexapoda. 



This supposition that the tracheae are acicular glands is in itself 

 not improbable. The acicula, as has already been mentioned, are not 

 so much protective bristles as supporting structures for the parapodia, 



