CARDITA LACUNAE. 53 



Stoliczka and Zittel, briefly, and as respects the teeth not very clearly. I 

 have therefore given a generic name to this shell with much doubt, espe- 

 cially as Gonodon has hitherto been known only from Jurassic strata. Coll. 

 Merrill. 



Locality and Position. — Beirut district ; from a yellow arenaceous marl, 

 probably Turonian. 



Cardita lacunar, sp. no v. 



Plate V, liss. 1 a, b, c, d, e. 



Testa parva, orbiculato-qnadrangularis, paido longior quam attior, tumida, ince- 

 quUateraUs, umbonibus obliquis incurvis approximatis antemedianis instrueta: margo 

 aniieus insinuatus, roiundatus, posticus abrupte truncalus, cardinalis retrorsum lente 

 decUvis, ventralis cequaliter arcuaius : superficies costis radiantibus quaternis denis 

 compressis squamosis eleganier insculpta; squamae suherectas, rotundce, imbricalce ; 

 irderstitia lata, profunda, in valva sinistra duo posteriora lamellis transversis specie 

 lacunarium divisa : lunula parva, cordiformis utrinque cavata, medio parurn elevata : 

 signa interna incognita. 



Shell small, roundish-quadrangular, a little longer than high, tumid, ine- 

 quilateral, furnished with oblique, incurved, closely approximate antemesial 

 umbones : anterior margin insinuate, rounded, the posterior one abruptly 

 truncate, the hinge margin gently sloping backward, the ventral regularly 

 arcuated: surface elegantly sculptured with fourteen radiating, compressed 

 scaly ribs ; the scales suberect, round at the end, imbricate ; interspaces of 

 the ribs wide and deep, the hinder two upon the left valve divided by trans- 

 verse lamella? after the manner of lacunaria: lunule small, cordate, excavated 

 on each side, elevated in the middle. Characters of the interior unknown. 



Five examples, almost uniform in size, and all retaining the test entire. 

 Length. 85 mm.; height, 7.1 mm.; thickness. 6 mm. 



In all the specimens the posterior cardinal margin of the left valve is 

 conspicuously higher than that of the right ; and the interspace of the 

 hindermost two ribs of the same valve is divided by delicate and flexuous 

 transverse lamellae into four-sided pits, panels, or compartments, widest in 

 proportion to their length toward the beaks and narrowing downward. This 

 structure, which suggested the specific name, is upon the right valve barely 

 indicated, never complete. Coll. Bird. 



Locality and Position. — Probably from the vicinity of Abeih, and from the 

 Turonian marl. 



