© 
FOSSILS OF THE CAMBRIAN. 9 
iv) 
postero-lateral angle, as Mr. Ford has pointed out for the form, fig. 11, of O. 
asaphoides, and also in the genus Paradoxides. 
Attention is again called to the direction of the facial suture back of 
the eyes, in figs. 3 and 4, and the position and obliquity of the eyes in re- 
lation to the median line of the glabella, characters of Paradowides, as seen 
in P. spinosus. Of all the species of the latter genus, P. Kjeruifi* alone 
shows the presence of an ocular ridge uniting the eye and the frontal lobe 
of the glabella, fig. 15 (a), a feature so prominent in the young of O. Howelli, 
as well as the small, rounded protuberance between the eye and the glabella, 
shown in Linnarsson’s fig. 2, of P. Kjerulfi. The latter character Mr. Ford 
discovered in the young of O. asaphoides, and noted its resemblance to the 
same in P. Kjerulfi. The ocular ridge, a feature in the latter that is per- 
manent, is also present in the young of O. Howelli, but disappears in the 
adult, adding in this another link to the argument so admirably brought 
forward by Mr. Ford to show the genetic relation of the two genera. 
Résumé.—The study of the head of Olenellus Howelli proves: 
First. That in certain individuals of this species the existence of em- 
bryonic features continues long after the individual has reached the size at 
which such features are usually lost in the process of development of other 
species of the genus. 
Second. That in individuals otherwise developed equally in all respects 
some one of them may have a characteristic feature, such as the eye or the 
genal angle, developed to a greater or less degree than in the others, and 
that this feature may persist even after the individual having it has passed 
in size or other characters the stage at which it is usually lost 
Third. That the development of certain characters went on in an unequal 
degree in the corresponding parts of the same individual, and, finally, that 
certain features present in the younger individuals and disappearing during 
the subsequent growth are permanent features in some species of the genus 
Paradoxides. 
4Ofversigt af Kongl. Vetenskaps-Akademiens Férhandlingar, N:o. 6, Stockholm, p. 790, Tafl. 
xvi, figs. 1, 2. 1871. 
