74 ■ SYNOPSIS OF THE CHARACTERS OF THE 



This little species bears a resemblance to some of the varieties of Cucullaa unilateralis, Sow., but is much 

 smaller, more compressed, and is, moreover, distinguished from this and all the other Devonian Cucullcea's by 

 its narrow, pointed beak. Length four lines, width four lines. 



MoDiOLA. Lam. 



Gen. Ch. — Transversely oblong; beaks small, not terminal; anterior side small, gaping, to allow the pas- 

 sage of the byssus ; no hinge-teeth. Some of our fossil species, as for instance, the iV/. microcephala, have 

 the thin, inflated, rugged shell, and elevated diverging ridges oi Lanistes, but retaining the angulated hinge- 

 line of Modiola, forming a passage from one genus to the other : others shew clearly the teeth of the genus 

 Brachydontes, Sw., indicating a passage towards Nucida, Lam. 



Modiola amygdalina. Phil. 



Modiola amygdalina. Phil. Pal. Fos. 



Sp. Ch. — Transversely ovate; rather more than twice as wide as long; very gibbous; beaks large, in- 

 curved, terminal ; anterior side forming a very small lobe under the beaks ; posterior side obtusely rounded ; 

 surface marked with sharp, rather distant, concentric striae. 



This curious httle species has a small lunette beneath the beaks : the concentric strice vary slightly in their 

 distance from each other. Lencrth three hues, width eig-ht lines. 



Modiola angusta. Portk. 



Modiola Macadami var. angusta. Portk. Geol. Eep. 

 Sp. Ch . — Transversely elongate ; three times as wide as long ; very gibbous, cyHndxical ; extremities rounded ; 

 dorsal and ventral margins slightly convex ; surface marked with fine, sharp, concentric striae. 



Modiola concinna. MCoy. (PL XI. fig. 28). 



Sp. Ch. — Transversely oblong, twice and a half as wide as long; gibbous; dorsal and ventral margins 

 nearly parallel ; beaks tumid, close to the anterior end ; anterior end very short, rounded ; posterior end obhquely 

 subtruncated ; surface with about nine or ten flat, imbricating lamellae, each fringed by strong, sharp, longitu- 

 dinal striae, finest toward the anterior end. 



This beautiful shell is obviously i-elated to that section of the recent ModiolcE, with small, tender, yet 

 rugged shells, destitute of byssus, and living habitually in various species of Alcyonuim, and nearly allied 

 animals, of whose existence at the period of the carboniferous Hmestone, we have no other proof Lengtli four 

 and a half lines, width ten Unes. 



Modiola divisa. M'Coy. (PL XI. fig. 30). 



Sp. Ch. — Transversely ovate, twice as wide as long, gibbous, beaks tumid, close to the anterior end; hinge- 

 margin elevated, rectangular, as long as the shell is wide ; anterior end short, rounded ; posterior end subtrun- 

 cate, rounded ; a small notch, or sinus in the abdominal margin, frofa whence a deep sulcus extends entirely to 

 the beak ; surface very finely wrinkled transversely. 



The deep, narrow sulcus, extending from the beak to the opposite margin, and dividing the anterior from 

 the posterior portion of the shell, distinguishes this little species from any other of the genus. Length one and 

 a half lines, width three fines. 



Modiola lingualis. Pliil. 



Modiola lingualis. Phil. Geol. York. 

 Some obscure specimens of this shell have occurred. They are transversely elongate, about four times as 

 wide as long ; dorsal and ventral margins convex ; hinge-line very short, scarcely angulated ; anterior end narrow. 



