June, i9-'i.] CrA.MPTOX: EvOLUTIOX OF THE AnT11R0P(I»A. 77 



portant in Apsciidcs. There is also a marked tendency toward the 

 reduction of the palpus "en," and. in fact, the palpus is completely 

 lost in the Crustacea shown in Figs. 2 and 6; and the condition ex- 

 hibited by the crustacean shown in Fig. 6 (Plate VI). which has not 

 only lost its mandibular palpus, but also has no gnathofimbrium or 

 lacinia mobilis (i.e., the structures labeled "en." " <if " and "hn" in 

 Fig. 3, Plate VI) is very suggestive of that exhibited by the insect 

 representing the next stage in the evolution of the mandible. 



ep 



Fig.8 



Textfigure 7. First parapodium of Laodice rubra (gill " ep " is present 

 in the second parapodium, not the first). Textfigure 8. First thoracic limb of 

 crustacean, based on condition found in Syncarida. 



As was mentioned al)Ove. the mandible of the crustacean shown 

 in Fig. 6 (Plate \l] is more like that of the insect shown in Plate 

 VI, Fig. 5 (or in textfigure 6) than is true of the mandible of the 

 crustacean figured in textfigure 5, since Vcrhins (Fig. 6) has lost 

 its mandibular palpus, and has only the incisor process " /// " and 

 molar process '' mo " in the distal region of the mandible — as is also 

 true of the insect shown in Fig. 5. On the other hand, it is a very 

 simple matter to compare the parts of the mandible of the insect shown 

 in textfigure 6 (which is the same insect as that shown in Fig. 5, 

 Plate VI) with the preceding crustacean stage shown in textfigure 

 5, and it is preferable for the sake of comparison, to use a crustacean 

 in which the mandibular palpus is still retained, in order to demon- 

 strate that there is no part of the insect's mandible comparable to the 

 mandibular palpus of the crustacean. 



In comparing the mandible of the insect Machilis (textfigure 6) 

 with that of the crustacean Apseudes (textfigure 5) it may be seen 



