316 PROCEEDINGS OF THE ACADEMY OP 



hinge margin ; surface marked only by moderately distinct lines of growth. 

 Posterior muscular impression oval, well denned ; pallial line distinct, and 

 provided -with a rather deep, horizontal sinus, about one-third longer than wide. 



Length, 2-04 inches ; height, 1-50 inches ; breadth or convexity, 1 inch. 



Mr. Conrad has described a Mactra similar to this, under the name of M. 

 albarea, from the Tertiary rocks on the Columbia River. (Am. Jour. Sci. vol. 

 5, sec. ser. p. 434.) The species before me, however, is proportionally longer 

 transversely, and less gibbous. It also differs in being destitute of a distinct 

 angle down the posterior umbonal slopes. 



The specific name is given in honor of Mr. George Gibbs, the geologist of the 

 North-Western Boundary Survey. 



Locality. The specimens were all found in a loose piece of hard greenish 

 gray sandstone, on the Straits of Fuca; and I have been unable to determine 

 whether they belong to the Cretaceous or Tertiary epoch. I incline to the 

 opinion, however, that they belong to the latter. 



CEPHALOPODA. 



Baculitesinornatus. Shell of medium size, straight, very gradually taper- 

 ing, and moderately compressed; section and aperture regularly ovate, the 

 ventral side being a little more broadly rounded than the dorsal ; lip deeply 

 sinuous on each lateral margin, near the ventral side, and provided with a long 

 linguiform extension on the dorsal margin, while its ventral edge presents a 

 nearly semicircular outline. Surface entirely destitute of costae, nodes, or 

 undulations ; lines of growth moderately distinct, and curving gracefully 

 parallel to the prominences, and deep sinuosities of the lip. 



The largest fragment of this species in the collection measures 1-49 inches 

 in its greater diameter, and 1-13 inches in its smaller, and judging from its very 

 gradual taper, appears to have been, when entire, as much as 15 or 16 inches in 

 length. It differs from B. ovatus of Say, in being entirely destitute of undula- 

 tions, at all ages, and in being usually smaller, and proportionally more slender. 

 It also presents differences in the details of its septa, lobes and saddles, which, 

 however, cannot be clearly explained without the use of figures. 



Locality. Sucia Island, Gulf of Georgia. 



Bac0lites occidentalis. Baculites ovatus (Say ?) Meek, 1857, Transactions 

 Albany Inst. vol. iv. p. 48. 



Shell straight, and very gradually tapering ; section subtrigonal to- 

 wards the larger end, but becoming more nearly ovate towards the smaller 

 extremity; ventral side flattened, ventro-lateral margins angular; sides con- 

 verging with a slightly convex outline from the ventro-lateral angles, to the 

 very narrowly rounded, or obtusely angular dorsum ; aperture subtrigonal ; 

 ventral projection of the lip nearly semicircular; that of the dorsal side much 

 longer, somewhat wedge-shaped, but a little rounded at its narrow extremity ; 

 lateral sinuses of the lip rounded, with a long, nearly straight, oblique margin 

 on the dorsal side. Surface ornamented with rather small, regular undula- 

 tions or costae, extending across from the ventro-lateral angles to, or beyond, 

 the middle of each side, with a regular curve parallel with the margins of the 

 lateral sinuses of the lip ; fine regular lines of growth are also seen traversing 

 the shell parallel to the dorsal and ventral projections, and lateral sinuosities 

 of the lip. 



The specimens examined are all too imperfect to give accurate measure- 

 ments, but so far as can be determined from the taper, of those most nearly 

 entire, an individual measuring 1-45 inches in its greater transverse diameter, 

 and one inch in its smaller do., near the aperture, must have been about 14 to 

 16 inches in length. 



The peculiar flattening of the ventral side of this species, is a character that 

 will at once distinguish it from any other Baculite with which I am acquainted. 



[Oct. 



