70 PROC. ENT. SOC. WASH., VOL. 24, NO. 2, MAR., 1922 



comparing the parts of the maxilliped of the crustacean shown 

 in Fig. 10 with those of the maxilla of the insect shown in Fig. 1 1 , 

 since there is a wonderfully close resemblance in the relative 

 sizes, etc., of the segments in the mouthpart-limbs shown in 

 Figs. 11 and 10, enabling us to compare the parts without the 

 least difficulty, so that having in our possession the key furnished 

 by the mouthpart-limb shown in Fig. 10, the veriest tyro would 

 be able to homologize the parts of the insect's maxilla shown 

 Fig. 1 1 (and hence the parts of the maxillae of all insects as well); 

 and we are thus able at once to demonstrate the fallacy of the 

 generally accepted view that the maxillary palpus of an insect 

 represents the exopodite of a crustacean limb, or that the galea 

 and lacinia of an insect's maxilla represent the endopodite of 

 such a crustacean limb, for the basal segment cp of Fig. 1 1 

 clearly represents the basal segment cp of Fig. 10, while the 

 second segment bp of Fig. 11, which is large and bears an endite 

 be, clearly corresponds to the second segment bp of Fig. 10, 

 which is also large and bears an endite be. The third segment 

 ip of Fig. 11 is smaller and bears an endite " ie," and is clearly 

 homologous with the third segment ip of Fig. 10, which is also 

 smaller and bears an endite ie. The fourth segment mp is the 

 smallest of all the segments in both Figures 11 and 10, while 

 the fifth segment crp is long and slender in both, and is followed 

 by a shorter slender segment pp in both figures. The terminal 

 segment dp is still shorter in both figures, but in Fig. 10 it 

 bears a terminal claw not present in Fig. 11 although the 

 terminal claw is also absent in many Crustacea as well as in the 

 insect shown in Fig. 11. The remarkable resemblance even 

 to the details of the relative sizes of the different segments com- 

 posing the mouthpart-limbs thus enables us to establish beyond 

 all possibility of doubt, that the maxillary palpus en of Fig. 11 

 represents the endopodite en of Fig. 10, while the galea ie and 

 lacinia be of Fig. 11 are clearly the representatives of the endites 

 ie and be of the third and second segments of the mouthpart 

 limb shown in Fig. 10, thus showing conclusively that it is 

 folly to claim that the palpus of an insect's maxilla represents 

 the exopodite of a crustacean limb, and that the galea and 

 lacinia represent the endopodite of such a biramous limb! 

 Furthermore, a comparison of the parts in Figs. 11 and 10 would 

 indicate that a four-jointed maxillary palpus, such as that 

 labeled en in Fig. 1 1 probably represents the condition typical 

 for insects in general or that four was probably the "ancestral" 

 or primitive number of segments entering into the composition 

 of the palpi of the maxillae of the first insects. 



By comparing Fig. 11 with Fig. 12 it may be seen that the 

 basal segment or cardo cp of Fig. 12 is proportionately much 

 smaller than in Fig. 11, while the second segment or stipes bp 



