ADDENDA. 



Etyus similis, miJd. Plate I, fig. 12 ; and XI, fig. 15. 



At page 6 I referred to a supposed variety of Etyus Martini, of which also a figure, 

 representing the orbits, is given in Plate I, fig. 12. The examination of two additional 

 specimens with which I have been favoured by Mr. Carter, has, however, convinced me 

 that these, with the former, belong to a distinct species, to which, from its great similarity 

 to E. Martini, I have given the above name. 



The ground of the carapace is more minutely granulated than in the former species. 

 The tuberculation is considerably different, the whole portion anterior to the nuchal furrow 

 being studded, somewhat irregularly, with distinct tubercles. The nuchal furrow is more 

 waved in its course across the carapace, and it is deeper and broader ; the regions generally 

 are more elevated ; the teeth of the latero-anterior margin are more regular and prominent, 

 but without the distinct terminal tubercle which exists on each of the slight lateral projec- 

 tions in the former. All the specimens examined were imperfect at the posterior portion 

 of the carapace, but it appears, from the proportions of the regions generally, that this 

 species is somewhat broader in proportion to its length. 



It occurs with the other species in the Cambridge Upper Greensand. 



EucoRYSTES Carteri, var. Plate XI, fig. 16. 



Mr. Carter has favoured me with the opportunity of examining and figuring a very 

 interesting variety of Eucorystes Carteri, in which the posterior half of the carajjace 

 corresponding with the scapular arch is sculptured in the same manner as the anterior 

 half, as figured in Plate II, figs. 14 and 17. In this, the only existing specimen, there is, in 

 addition to the sculpturing before described, a median longitudinal ridge, and one on each 

 branchial region. These are linear, fiattened, and granulated as the others. Whether this 

 may be considered as the normal condition of the species or not it is difficult to determine. 



