512 C. T. Trechmann— 



The decoration of the sides of the lower valve and surface of the 

 lid is alike in all these shajoe variants. That of the sides consists of 

 longitudinal incised sulci, between which are rai,sed ridges, which 

 are often striated longitudinally by smaller parallel sulci, and cut 

 transversely by small growth interruiotions. The decoration of 

 the top valve is of a much more complicated nature than that of 

 B. monilifera, and consists of irregular rounded ribs radiating from 

 a central apex, often breaking tip into two or three divergent ribs, 

 and between them cross ribs arranged parallel with the margin of 

 the valve. Between these, again, more smaller ribs diverge, forming 

 a reticulate or honeycomb-like design. The lid in this species is 

 stronger and thicker and less irregular in surface than it is in 

 B. monilifera, and the two apertures or foramina of the lid, 

 corresponding to the position of the first and second pillars in the 

 living chamber, are more or less well shown (PI. XIX, Fig. 1). The 

 depressions or pits of the surface of the lower valve round the living 

 chamber are very regular, numerous, and sharply defined, and consist 

 of rectangular cavities generally elongate in a direction parallel to 

 the margin of the shell. The shelly walls bounding these cavities 

 parallel to the margin are sharp-edged, and pass generally from one 

 node to another of the moniliform rays. 



Locality. — Barrettia bed, Green Island, Jamaica. Maestrichtian (?). 



Barrettia sparcilirata Whitfield. 

 1897. Bull. American Mus. Nat. History, vol. ix, p. 245, pis. xxxvi, xxxvii. 



This species, which is recorded only from Logic Green, is described 

 as having twenty-three rays and a diameter of 5 or 6 inches, and to be 

 of a cylindrical or turbinate shape. Whitfield records that a portion 

 of the external surface of the lower valve is visible on this species, 

 the only example among his collection which exhibited this feature. 



The fewness of its rays rather seems to suggest some connexion 

 with the genus Pironoeci, but in that genus the radial infoldings 

 are not cut up into " strings of beads " as they are in Barrettia. 



Cardita (Venericardia) cf. suhcom.planata d'Archiac. PL XX, Fig. 4. 



1853. Description des Anim. fossiles du groupe nummulitique de I'Inde, p. 253, 



pi. xxi, figs. 10, 11. 

 1897. Noetling, " Fauna of the Upper Cretaceous (Maestrichtian) Beds of 



the Mari HiUs " : Pal. Ind., ser. xvi, vol. i, pt. iii, p. 46, pi. xii, 



fig. 3. 

 The right valve of a rather flattened and compressed Cardita 

 seems to be approximately identifiable with the above Indian species. 

 Its outline is nearly semicircular, but compared with the figure of 

 d'Archiac, the Jamaica shell seems rather more rounded, the beaks 

 rather more pointed and more anteriorly situated, and the ribs 

 rather broader than the interspaces between them, and the lunule 

 slightly more excavated. There are eighteen or twenty gently 

 curved radiating ribs. 



Dimeyisions.— Length and height 20 mm. 



