102 BRITISH CAMBRIAN TRILOBITES. 



The figure accompanying Salter's description is a restoration, and is evidently 

 based upon a misapprehension of the specimen. It does not even correspond 

 with the description. Apparently the artist thought that the whole of the 

 glabella was exposed; and consequently he represents it as clavate in form, 

 narrow at the neck-segment and expanded in front. In the actual specimen the 

 neck-furrow arches forwards from the left axial furrow, and at the right-hand 

 edge of the specimen it has only just begun to curve back to the right axial 

 furrow. It is clear in fact that not much more than half of the basal portion of 

 the glabella is visible ; and if the remaining part is restored, as shown in outline 

 • in Plate XII, fig. 4, there is little, if any, increase in width towards the front. 



The figure is also inaccurate in other respects. It leaves a wide space between 

 the end of the glabella and the front margin, while Salter states that the glabella 

 all but reaches the front margin. The eye is represented as in the middle of the 

 cheek, whereas, in fact, it is very close to the anterior end of the glabella. Salter 

 himself says that it is near the glabella. 



Owing to the evident imperfection of the figure and description, neither 

 Brogger 1 nor Reed 2 expresses any decided view as to the generic position of the 

 species. Brogger suggests that it may be allied to Gyclognathus, and Reed says 

 that it must be removed from Conocoryphe and placed in the Olenidae. 



Horizon ami Locality. — Upper Tremadoc : Garth, Minffordd, near Portmadoc. 



Genus BELTELLA, novum. 



The three species next described are very closely allied to one another. 

 There are, indeed, considerable differences in the form of the glabella, but for the 

 reasons explained in the account of Deltella uerisimilis I believe that some of 

 these differences are sexual and not specific. 



They were ascribed by Belt and Salter, with more or less hesitation, to 

 Conocoryphe; but Belt clearly recognised that these Lingula Flag and Tremadoc 

 forms are distinct from the true Gonocoryphe of the lower part of the Cambrian, 

 and he looked upon them as definitely belonging to the Olenida?. 



In their general characters they approximate most closely to Olenux, in the 

 wider sense of the name, but they do not fall under any of the recognised 

 genera or sub-genera into which (Hen us sensu lato has been divided; and in 

 some characters they approach the Conocephalida3. I have accordingly, with 

 some reluctance, placed them together under the new generic name Beltella. 



Most of the specimens are flattened, but it is probable that originally the whole 

 animal was decidedly convex. The head is more or less semicircular in form, with 



1 Verb. d. Euloma-Niobe-Fnunn,, Nyt Mag. f. Naturv., vol. xxxvi (1897), p. 203; separate copies 

 (1896), p. 40. 



2 Geol. Mag. [4], vol. vii (1900), p. 255. 



