134 SYNOPSIS OF THE CHARACTERS OF THE 



This little species is not uncommon, in company with the S. crispa, S. speciosa, &c. Length three lines, 

 ■width five lines. 



Spieifera quinqueloba. M'Coij. (PL XXII. fig. 7)- 



Sp_ c/i._ Ventral valve semicircular, twice as wide as long, with five nearly equal, rounded, distant, ra- 

 diating ribs, crossed by sharp, regular, concentric lines of growth. 



This species is distinguished from the S. pfi/chodes, Dal, which has also five lobes, by its greater width 

 and transverse stria; ; from the S. crispa of the Silurian rocks (allied to the S. amUijptera, Phil), by its greater 

 width and acute cardinal angles; from the S. crispa of the Eifel and Irish carboniferous slate, by the small 

 number and roundness of its distant, radiating ribs. Length three lines, width six lines. 



Spirifera rhomboidea. Phil. 



Spirifera rhomboidea. Phil. Geol. York. 



Sp, C/i.— Fusiform, rhomboidal; width exceeding twice the length; depth exceeding the length of the 

 small valve ; mesial fold defined, rounded, bearing six round, smooth, radiating ribs ; about twelve rather 



larger ribs on each side. 



This is not an uncommon species ; the long, cylindrical sides render it very striking. Length seven 



lines, depth six lines, width one and a quarter inches. 



SriEIFER ROTUNDATA. SoW. 

 Spirifer rotundatus. Sow. Min. Con. — Spirifera rotundata. Phil. Geol. York. 

 i^p.CVt.— Transversely oval, depressed; cardinal area narrow; beaks approximate ; about twelve, broad, 

 flattened (occasionally branched) ribs, on each side the mesial elevation, which is large, rounded, and 



smooth. 



The width of this species is about once and a half the length, the depth half the width ; the lateral radia- 

 tions are broad, and much flattened, usually branched; the mesial ridge smooth, rounded, usually with a sulcus 

 down the middle ; the corresponding hollow has obscure ribs, somewhat smaller than those of the sides (I 

 have seen a few specimens in which both the mesial hollow and ridges had obscure ribs). This very common 

 species is united by Von Buch to the Spirifera ostiolata, from which, however, it difiers very widely. Most of 

 our English authors have confounded it with the Sjnrifer pinguis of Sowerby (see Brachythyris pinyuis). 

 It is not' the Anomites rotundatus of ISIartin. Length two inches three lines, width three inches. 



Spirifera rudis. Phil 



Spirifera rudis. Phil. Pal. Fos. 



A few obscure fragments, resembling Professor Phillips' figure more than any other species I am acquainted 

 with, have occurred, but they are too imperfect to furnish a description, nor is any definition of the species 

 published. 



Spirifera speciosa. Bronn. 



Spirifer speciosus alatus. Broun. Leth. Geog. 



Sp. C%.— Transversely elongated, fusiform, gibbous; sides conical, pointed ; cardinal area narrow, with 

 parallel sides ; mesial fold broad, rounded ; about ten narrow, rounded, prominent ribs on each side ; entire 

 surface crossed by regular, imbricated, erect, scale-like lamina; of growth. 



This beautiful shell is abundant in the Eifel, and certain districts in Ireland, I can see nothing to distin- 

 guish the S. costata of Sowerby from this species. 



