-mars.] PALEONTOLOGY CEETACEOUS FOSSILS. 301 



portion of the shell, which projection has the shape of a Norman shield, 

 as seen by front view when both valves are in then natural position, 

 and which seems to have been occupied by a much wider gape in the 

 younger than in the adult condition of the shell ; both umbonal grooves 

 distinct, both upon the outer surface and upon that of the stony cast ; 

 anterior groove broader and deeper than the other, but both are slender ; 

 besides the two umbonal grooves there is another somewhat broader 

 groove or furrow, extending with a broad, downward curve from the 

 posterior side of the beak to the posterior end of the shell. This groove, 

 like the other, is distinctly traceable upon the outer surface, but is more 

 distinctly seen upon the stony cast. 



Abroad, subcircular, cake-like umbonal accessory valve covers the beaks 

 and the space between them, the valve being divided by a suture into two 

 nearly semicircular pieces, so neatly that it is hardly perceptible until 

 the valves are slightly displaced. The margins of the principal valves 

 between the beaks and the Norman shield-shaped projection are narrowly 

 but abruptly everted, which, with the beaks above and the borders of 

 the projection below, bound a distinctly hollowed space on each side and 

 below each beak. Besides the grooves before mentioned, the surface is 

 marked by fine concentric, distinctly raised lines on each side of the shell, 

 but they are less distinct upon the surface of the Norman shield-shaped 

 projection than elsewhere. Between the posterior groove or furrow before 

 mentioned as ending at the posterior margin of the shell and the dorsal 

 margin, the surface is occupied by strong, irregular scales and laminae 

 that were successively left as the shell increased in size. 



Length, 13 mdlimeters; greatest height, 7 millimeters; breadth at 

 front, 6 millimeters. 



Since publishing the original description of this species (loc. tit.), I have 

 had opportunity to examine additional examples, which show its charac- 

 teristics more completely than they were known before. This is shown 

 in the modified description of the species and the reference of it to Para- 

 pholas Conrad, instead of to Turnus Gabb, as was doue before. Although 

 its outward form is quite different from that of the typical species of Tur- 

 nus, I then believed the posterior umbonal groove, which I saw only in 

 the stony cast, to represent an internal rib, and not a groove in the 

 test. Mr. Gabb also mentioned the discovery of fragments of tubes as- 

 sociated with his examples of Turnus, which led him to believe pertained 

 to those shells, thus relating them to Teredo on the one hand, while other 

 characters connectedthem to the Pholodidcc. I had also detected fragments 

 of tubes associated in the same mass of rock with this species, but later 

 examination leads me to believe that they belong to a true Teredo, al- 

 though the valvular portions have not been discovered. These tube-like 

 specimens, together with the shells here described, were contained in 

 small, irregular, nodular, impure lime-carbonate masses, of three or four 

 inches in diameter, the somewhat distorted tubes traversing them irreg- 

 ularly; but most of the specimens here described were found with their 

 anterior ends all pointing toward the center of the nodules, with their 

 posterior ends pointing outwards, and placed near the outer surface 

 of the nodule. The nodules were found to contain a few fragments of 

 unmistakable fossil wood. It is probable that this wood was bored by 

 both the Teredo and the Parapholas, and as that decayed, the shells formed 

 a nucleus around which the lime-carbonate formed the nodular masses in 

 the shale in which they were discovered. 



I am not fully satisfied now that this species really belongs to Parapho- 

 las Conrad, or to any other published genus; but I refer it to Parapholas 

 mainly because Stoliczska has adopted that name for some Cretaceous 



