Smyth — Faunal Zones of Rush-Skerries Carboniferous Section. 561 



Transverse section (with diam. 21mm.): — Central area lemon-shaped, 

 bounded by a strong wall, and containing a mesial plate. The plate is 

 bordered by close-set, short lamellae, giving it a centipede-like appearance. 

 These short lamellae are embedded in stereoplasm. Only some of them are 

 produced beyond tiie innermost tabular intersection. The produced ones are 

 continued across one or more of the few (5 or 6) tabular intersections, several 

 reaching the outer wall of the area. This wall is composed of two tabular 

 intersections. Tlie inner of these is thickened on its outer side, and from it 

 arise numerous lamellae, only some of which reach the outer tabular inter- 

 section. The remainder of the section is extremely simple, consisting of a 

 thick outer wall, from which arise two series of septa. The minor septa are 

 very short. The major septa reach the central area, near which they are 

 spirally deflected. In the septate area there are only two or three tabular 

 intersections, and no vesicles. (One row of vesicles is developed near the 

 edge of the calyx.) 



In a younger transverse section the wall of the central area is composed 

 of a single thickened tabular intersection, on which lamellae cannot be 

 detected. In a still younger section (fig. 2b), this wall has disappeared, and 

 the ends of the major septa become merged in the thickening of the mesial 

 plate. 



A longitudinal section in the calyx shows that the tabulae are extremely 

 steep in the central area, and form a high boss in the calyx. 



Producttis cf. si(b-/aevis, de Kon. 

 Lane Limkstone. 

 Two species are included under this designation. All the specimens are 

 extremely fragmentary. 



(1) Several specimens of this form were obtained in the upper parts of 

 the Lane beds. They agree very well, as far as they go, with P. sub-laevis 

 from O2 of Belgium. This is tlie form, a water-worn specimen of which 

 was recorded by Yaughan as P. humeroHus} 



(2) A single specimen, resembling P. sub-laevis in form and ornament, 

 but with a quite thin shell (cf. P. Christiani, de Kon.). 



Two similar forms occur at Olitheroe (Lancashire) above a Cj fauna. 



Chonetes squamata, sp. nov. (PI. XXXYI, fig. 15.) 

 Rush Conglomerate, li 11 & 12. 

 Length c. 18 mm. Width c, 28 mm. 

 Ribbing moderately coarse (c. 17 ribs in 1 cm. near anterior margin), ribs 



' Quart. Journ. Geol. Soc, vol. Ixiv, 1908, p. 438. 



4 U 2 



