160 DR G. W. LEE ON 



Closer comparison is not possible, as the internal characters of Phillips' type- 

 specimen are not known ; the species described here has no dental plates, and the surface 

 is apparently not punctate. 



Martinia brucei sp. nov. (PL I. figs 13-13e.) 



This shell is depressed, sub-rectangular, with width slightly in excess of length ; the 

 hinge-line is shorter than the greatest width of the shell. The sulcus and the mesial fold 

 are indistinct. Both valves are very shallow and of equal depth, and the beak is not 

 much incurved. If I am right in assuming that the two specimens described here under 

 this name really belong to the same species, then the ornamentation varies considerably 

 with age ; on the small one it consists of eighteen rounded ribs, whilst on the larger speci- 

 men there are thirty such ribs, a few of which are due to bifurcation. In both, the surface 

 shows an extremely minute pitting, and is covered with sharp, close-set lines of growth 

 quite visible to the naked eye. The area is very narrow and there are no dental plates. 



The smaller specimen, in which both valves are in apposition, has the following 



dimensions : — 



Length . . . . .13 mm. 



Width ..... 13-5 „ 



Depth . . . . . 6 "5 „ 



The larger one is a pedicle-valve 15 mm. long and 18 mm. wide. 



I do not know any Carboniferous Martinia which could be considered as closely 

 allied to this species. The nature of the ribbing and the lack of distinct sulcus and 

 fold give it a general resemblance to the young stage of Martinia ? inteyricosta 

 (Phillips), as figured by Davidson (loc. cit., pi. ix., figs. 17, 18), from which it differs, 

 however, in having a much narrower area and the pedicle-valve not more convex than 

 the brachial one. There is also a curious superficial resemblance between the smaller 

 specimen and the otherwise very different Martiniopsis baschldrica Tschernyschew,* 

 this being a striking example of close external resemblance between two forms which, 

 according to the modern views, are to be considered as generically distinct on account of 

 their internal characters. 



Martinia sp. (PL I. figs. 15-1 5a.) 



Two pedicle-valves, belonging to a species apparently undescribed, are characterised 

 by their rhomboidal shape, linguiform sinus, and peculiar ornamentation consisting of 

 faint ribs so flat that the narrow intervening sulci are more conspicuous than the ribs 

 themselves. No trace of ribbing can be seen on the cardinal slopes. The larger 

 specimen, 24 mm. long and about 20 mm. wide, has some twenty ribs ; the smaller 

 one, 8 mm. long and 7 "5 mm. wide, has only a little over half this number. 



The whole surface of the shell is covered with fine longitudinal strise regularly 



* Tschehnyrchew, Inc. cit., pi. Ixiii. fig. 1. 



