190 Prof. F. M^Coy on some new Carboniferous 



plicse of growth. Casts show the large anterior and posterior 

 adductor impressions distinctly connected by the simple pallia! 

 scar, together with faint traces of the concentric plicse of the 

 surface, crossed by microscopic, close, diagonal strise from the 

 beaks towards the respiratory margin ; also an impression of 

 the small cartilage ridge within the dorsal margin. Length 

 1 inch 7 lines, proportional depth greatest at middle of length 

 Y*(j^^, depth at posterior end j*^"^, from apex of beaks to ventral 

 margin y^^^^, length and width of anterior lunette j-^q, greatest 

 depth of both valves -^-^q, length of anterior end j^^j^. 



This is a smaller and much more obtuse species than the 

 L. dactyloides (M'Coy), the anterior end being proportionally 

 broader and more obtusely rounded ; the posterior end is also 

 less pointed, and the anal angle not elevated. I have not seen 

 the external shell of this species, except near the margins, and 

 here there is no trace of the distinct longitudinal or radiating 

 striation of that species, traces of which are however seen on the 

 internal casts. I dedicate this species to the Rev. Mr. Jenkinson 

 of Lowick, to whose labours we owe the most extensive and 

 beautifully perfect local collection perhaps ever made — particu- 

 larly instructive by the frequent exhibition of internal cha- 

 racters. 



Not uncommon in the impure carboniferous limestone of 

 Lowick, Northumberland. 



[Col. University of Cambridge.) 



Edmondia rudis (M'Coy). 



Desc. Rotundato-quadrate, very gibbous ; beaks very large, ob- 

 tuse, posterior end broad, subtruncate, very slightly oblique ; 

 posterior slope flattened, steep, undefined ; anterior end sub- 

 truncate, abruptly compressed ; ventral margin gently convex ; 

 hinge-line nearly as long as the shell, slightly raised, middle 

 of the shell with very unequal rugged plicse, parallel with the 

 ventral margin, anterior and posterior slopes evenly smooth. 

 Length 1 inch 1 line, proportional width -f-^^^, width of pos- 

 terior end /^%*, length of anterior end ^^5^0) depth of one 

 valve j%%. 



The short, quadrate, extremely gibbous fonn and unequal 

 rugged plicse distinguish this species from all other carboniferous 

 fossils that I know at a glance. There is often a sort of large 

 obscure pitting between the plicse. The cardinal cartilage ridge 

 is very thick, and nearly as long as the hinge-line or simple 

 erect cardinal margin. 



Rare in the impure carboniferous limestone of Lowick, North- 

 umberland. 



{Col. University of Cambridge.) 



