the cephalie horns are shorter and of an undetermin- 

 ed numtoer. We have in our plate given a large 

 nummer of pictures of natural size in order to show 

 the great differences not only in the number of a£- 

 tachment proces ses out al so in the ir form,a differ- 

 ence of very great signif icance,since men have hith- 

 erto supposed that they could separate species ac>- 

 cording to the nummer of the ir mouth-parts,as we 

 have previously noticed. 



On these f ins we discovered, Resides the many 

 younger stages, to which we will return later,nine 

 fully developed spec iraens which we tooic to "be sex- 

 ually ripe though none of them "bore egg-strings. 



These furnished the following lengths. . (a)cephal- 

 ic horns, .("b )neck. *(c )genital segment. ,( d)aodomen. 



Talple. 

 r 0f these the five last have only two horns whi 

 are seidom of the same length,while they al so stand 

 at dissimilar angles to the "body axis and are always 

 eurved; the four others have on the midline of the 

 dorsal surface a longer or shorter third horn, which 

 at least in spec imens 3 & M- is the shortest and 

 smallest; in 1 it is half as long as the lateral hor; 

 and in 2 almost equals them. .For closer com- 



parison with these proportions we inay add here that 



