PLATE 6. 



Papc. 

 Fig. 1. skkitla tenuicarinata 507 



A mass of rock, with portions of the shell-tubes exposed by the weathering away of the 

 surface (type-specimen). 

 Fig. 2. Pkionocvclus Woolgari 455 



An outline of a transverse .section of an outer volution near the aperture, showing the 

 wing-like lateral extensions of the costa-. (See also plate 7.) 



Figs. 3, a, c, and 6, 6. Mortoniceras Siioshonense 449 



3, it. A side view of the type-fragment. 



3, b. A peripheral view of the same. [By mistake numbered 6, b on the plate.] 



3, c. One of the septa, slightly more than natural size. 



Fig. 1. Scaphites veumiformis 423 



4, a. A side view of an internal cast, natural size (type-specimen). 

 4, b. Another view- of same, showing aperture, etc. 



Fig. 5. Scaphites Warreni 420 



A side view of the type-specimen, which is imperfect, and does not give an entirely clear 

 idea of the species. [See remarks and further illustrations iu text.] 



Fig* 6. Scaphites i.akv.e formis '. 418 



6, a. Side view, natural size, of the type-specimen. 



6, b. A peripheral view of same, turned a little obliquely. 



G, c. A septum of same, magnified to a little more than two diameters. 

 Figs. 7 and 8. Scaphites ventricosus 425 



7. a. View el' periphery and aperture, natural size, of type-specimen. 



7, h. A side view of same specimen. 



8, a. Ii Two views of a specimen, consisting of inner volutions, and believed to belong to the 



same species, 

 fi, o. A septum of same, slightly enlarged. 



