260 UNITED STxVTES GEOLOGICAL SURVEY OF THE TERRITORIES. 



It is probable that the concentric lines, where deflected upward in front 

 of the transverse groove, are minutely eremite ; but the only specimen seen, is 

 not in condition to retain such delicate markings, if they ever existed. The 

 posterior muscular scar is seen on the internal cast to be very narrow, elon- 

 gated, and placed near the dorsal margin, a little behind the middle of the 

 valves, while the deep pallial sinus is rounded at the extremity. 



It is not without some doubts that this shell has been referred to the 

 genus Martesia, as but a single imperfect specimen, showing no traces of the 

 accessory valves, has been seen. 



Locality and position. — Long Lake, near Fort Pierre, Dakota Territory; 

 in the Fox Hills group, or No. 5 of the Upper Missouri Cretaceous series. 



TEREDIDiE. 

 Genus TEREDO, Linnaeus. 



Synon. — Teredo, Pliny, SeHiiis, Adanson, and other prc-Liunsean authors. 



Teredo, Linnaeus (1758), Syst., ed. x, 651; and (1767) t&., ed. xii, 1267.— Brug. (1769), Encyc. 

 Meth., I, xii.— Spengl. (1792), Skrivt. Nat. Selsk., II, 99.— Lamarck (1799), Prodr., 90; 

 and (1801) Syst., 129.— Cuvier (1812), Ann. du Mus., XIX,*; and (1817) R. An., II, 

 493.— Lamarck (1818), Hist., V, 438.— Rang (1829), Man., 346.— Menke (1830), Syu., 

 2d ed., 122.— W. Thompson (1835), Jam., Edinbg. New Phil. Jour., XVIII, 121.— Swain- 

 son (1640), Malac, 364.— D'Orbigny (1845), Paleont. Fr. Terr. Cret., Ill, 301.— Gray 

 (1847), Proceed. Zool. Soc. Lond., part xv, 188.— H. and A. Adams (1856), Gen. Recent 

 Moll., 11,331.— Tryon( 1862), Proceed. Acad. Nat. Sci. Philad., 104; and (1873) Am. 

 Mar. Conch., 129, &c. 



Calohates, Gould (1862), Proceed. Boat. Soc. N. H., VIII, 280 ; and (1662) Otia Conch., 241.— 

 Tryon (1862), Proceed. Acad. Nat. Sci. Philad., 117. 



Eiyrn. — rtpriSuv, the ancient name of the ship-borer. 

 Type. — Teredo navialis, Linn. 



Shell small, globose-trilobate, gaping anteriorly and posteriorly ; surface 

 concentrically striated, and each valve crossed by a single more or less nearly 

 vertical umbonal furrow ; cardinal margin reflexed in front ; interior provided 

 in each valve with a long, slender, curved process for the attachment of the 

 pedal muscles. Burrow-tubes shelly, subcylindrical, sometimes concamerated. 

 Siphonal palletes of the animal simple, oblong, often truncated, entire; some- 

 times stilt-shaped, with the basal prolongation bony. 



H. and A. Adams include, as subgenera under Teredo, Xylotrya, Leach, 

 and Uperolus, Guettard ; but Mr. Tryon, who has given especial attention to 

 this and allied families of Mollusca separates the latter two groups as distinct 

 genera, on account of the solitary burrows, the compound pinnate nature ot 

 the siphonal palletes, and the broad valves of the first; and the club-shaped, 



