246 PALEOZOIC MOLLUSCA. 



the number of spiral keels on the upper surface. I should have 

 referred those specimens to the E, cornu-arietis (His.), but that 

 seems to have four large ridges to each w^horl, and no indication 

 is given in the figure or description of the spiral carinse on the 

 base. It much resembles some of the varieties of the Pleuroto- 

 maria umUlicata (Hall) from the Bird^s-eye limestone of New- 

 York, but is certainly distinguished by its smaller umbilicus, and 

 the three additional spiral keels on the base ; those latter are ge- 

 nerally best seen in the concavity left when the upper whorls of 

 a specimen are broken away (described from internal casts) . 



Common in the Bala slates of Cyrn-y-Brain, Wrexham, Den- 

 bighshire j and in the schists of Golden grove, Llandeilo, Caer- 

 marthenshire. 



[Col. University of Cambridge.) 



Maclureia macromphala (M^Coy). 



Desc. Discoid, sinistral, usually elliptical, of about three and a 

 half rapidly enlarging whorls ; spire depressed below the level 

 of the outer turn^ which bears an obscure, obtusely rounded 

 angulation, bounding the slightly oblique upper plane of the 

 shell ; circumference obtusely rounded ; under side having the 

 middle of the whorls obtusely angulated, thus denning a wide, 

 shallow umbilicus. Diameter 10 lines, proportional diameter 

 of last whorl y^^^^, height of last whorl y^^^^, diameter of umbi- 

 licus -^-^Q. Surface crossed by minute, thread-like lines of 

 growth, extending obliquely backwards from the suture, and 

 then crossing almost directly into the umbilicus. 



This little species is easily distinguished from the M. magna 

 by its very wide umbilicus (resembling that of the carboniferous 

 Euomphalus pentangulatus), and by the more rapidly enlarging 

 whorls, which also separate it from the imperfectly known 

 M. matutina and M. sordida (Hall), from the calciferous sand- 

 stone of New York. 



In the concretionary and schistose limestone of Craig Head 

 near Girvan, Ayrshire. 



(Col. University of Cambridge.) 



Encyliomphalus Scoticus (M^Coy). 



Desc. Discoid, flat, of one and a half gradually enlarging, widely 

 separated, spiral whorls ; back obtusely subcarinate, rounded, 

 lower side rounded, upper side wdth a flat space, bounded on 

 each side by one obscure keel, the outer one most distinct ; sur- 

 face crossed by rather distant sharp lines of growth, each pair 



