258 ENTOMOLOGICAL NEWS | XXxii, '21 



mologists apparently have but little knowledge of crustacean 

 anatomy which is at the very basis of the study of the first 

 principles of insect morphology, and should be taught to every 

 student beginning the study of entomology. 



Carcinologists. or students of the group Crustacea, apply 

 the term protopoditc to the fusion product, pr, of the two basal 

 segments (i. e., the fused coxopodite and basipodite ) of a 

 biramous limb, such as that shown in Plate V, Figs. 5, 7. 14. 

 16, etc., and they term the inner branch, en-, and the outer 

 branch, r.r, the endopodite and exopodite, respectively. The 

 modified limbs on either side of the telson, or terminal segment. 

 are called uropods; and the protopodites of the uropods. pr, 

 are located on either side of the anal opening in some Crustacea 

 such as the one shown in Fig. 14. The protopodite, pr, may 

 be slender, as in Fig. 7, or it may be broad and plate-like as in 

 Figs. 14. 10, etc. ; and the endopodite. en, and the exopodite. 

 r.r, may be many-jointed, as in Fig. 7, or they may each be 

 reduced to a single segment as in Fig. 14, en and r.r. There 

 is a marked tendency for the exopodite, ex, to become atrophied 

 (as in Figs. 5, 10, 16, etc.) in certain isopod Crustacea, and in 

 some of them the exopodite is completely lost. When the 

 exopodites of the uropods are lost in these Crustacea, the 

 endopodites resemble the cerci of insects very strikingly, and 

 the protopodites resemble the paraprocts or parapodial plates 

 situated on either side of the anus, and bearing the cerci, in 

 many insects. The foregoing facts led me to suggest (Canadian 

 Entomologist, Vol. LI I. 1920. p. 179) that the cerci of insects 

 represent the endopodites of the uropods of Crustacea, while 

 the paraprocts or parapodial plates of insects represent the 

 protopodite of the uropods of Crustacea, and the processes of 

 the parapodial plates (called "paraprocessi" in the article in 

 question) represent the exopodites of the uropods; and 1 would 

 here present the evidence which to my mind very clearly demon- 

 strates the correctness of this claim. 



In the triclactylid Orthopteron shown in Fig. 12, the eleventh 

 tergite, ep, is a plate situated above the anal opening, and on 

 either side of it is a basal plate labeled pr, which bears the cer- 

 cus, en, and a process labeled r.r. When the parts are spread 



