THE 



AMERICAN NATURALIST. 



Vol. XXXVIII. November-December , jg04. Nos. 455-456. 



THE EMBRYOLOGICAL UKX'KLOPM l-M ol' Hit: 

 SKELETON OF THI' HEAD OF HLATTA.' 



WILLIAM A. RILEY. 



Our knowledge of the embry()]o<,ncal development of the 

 sclerites of the head of insects is very iiKM-rr. With hut few 

 exceptions the subject has been treated 111 the ni(»t iiu idental 

 manner and the observations are few and .stattercd. 1 hi> is (hie 

 not only to the fact that attention has Inrn chivctedto the more 

 general features of insect enibr\ology, but i.s due al>o 10 ,1 Lu k 

 of sy.stematizing of our knowledge of the strueture oi ihe nead 

 of the adult insect and to the difrKulty ol deteniiinm.L; the 

 limits of the .sclerites before they beionie niinl\ diitmi/ed. 



Of all the .students ot insect embry.lo.L;) , lIeMnon> ( .m.l 

 •97), Janet ( 99), and Comstock and K-^Jji. ' ' lll"^!;^"^' Jj''^',''^.^^^^ 



workers differ radically in their eonchisioiis. 



It was in hopes of deterniimn- tlie rMndition> m .me m the 



more generalized of the i ' : - ' ' un<lertMMk Me 



study of the embryolo^; ' ^'""^ ^kekt'-n <il t u 



