wHiTEAves.] FOSSILS OP TRIAS8IC ROCKS OP BRITISH COLUMBIA. 133 



beak small, depressed, incurved and subccntral, but placed a little in 

 advance of the middle. 



Surface marked by flat, radiating ribs, wLich broaden outwards 

 rather rapidly in the centi-al portion of the valve. At and near their 

 outer termination, the central ribs are distinctly broader than the 

 spaces between them. The whole of the ribs ai-e invariably simple 

 and entire, but occasionally, though very rarely, a single and very 

 narrow rib is intercalated between two of the broader costtc. Charac- 

 ters of the interior of the valves unknown. 



I'imensions of the only specimen collected : maximum length, 

 sixteen millimetres ; greatest height of the same, twenty-one mm. 



Liard Eiver, about twenty-five miles below Devil's Portage, E. G. 

 McConnell, 1837 : a perfect and well-preserved left valve. 



This species seems to be well characterized by its broadly elliptical 

 form and flattened i-adiating ribs. It is apparently most nearly related 

 to the Monotis boreas of Oberg,* fj'om the Tj-ias of Spitzbergen (which 

 Mojsisovics say, i, a Fseudomonotis) and to the P seudomonoiis scutifor- 

 mis of Tellerf, from the Trias of Eastern Siberia, but both of these 

 species are nearly circular in marginal outline and ornamented with a 

 sculpture quite diff^^erent from that of M. ovalis. 



» 



Ii.4.LOBrA (Daonella) Lommeli, Wissman. 



Halohia Lommdi, Wissman.— 1841. Beitr. Petref., IV. Heft 22, tab. 6, fig. 11. 

 " " Hnmes.s. — 18.5.j. Densk. Kais. Akad. Wissensoh. IX, 52, taf. 2, 



fig. 17. 

 Aviada pecHniformis, Catullo. — 1847. Prodr- Pal. A.lpi. Ven., 73, pi. 1, figs. 1, 2. 3. 

 Posidonomya Lommeli, d'Orbign}-.— 1840. Prodr. du Paleont. Stratigr. Univ. 



L, 201. 

 ? Halobia dubia, Gabb.— 1864. Palseont. Californ., vol. I, p. 30, pi. 5, figs. 28 a, b. 

 Daonella dulna, Mojsisovics. — 1874. Ueber der Triasch. Pelecyp. Gatt. Daonella 



und Halobia, p. 22. 

 Halobia {Daonella) Lomrrieli, Meek,— 1877. U.S. Geol. Expl. 40th Par., vol. IV, 



p. 100, pi. 10, fig. 5. 



South side of Houston Stewart Channel, Q.C.I., nearly opposite Eose 

 Harbour, G. M. Dawson, 1878; and Liard Eiver about twenty-five 

 miles below Devil's Portage, E. G. McConnell, 188*7: a fiew detached 

 but almost invariably imperfect valves of a Halobia (or Daonella) with 

 subcentral beaks and broad, flat, radiating I'ibs. These agree very well 



* Om Trias-Forsteningar friin iSpetsberKen. Kongl. Svenak. Vetensk.-Akad. Ilandi., Bandet 

 U, No. 14, p. 17, Taf. 5. figs. 5 a, b 



tArktische Triasfaunen. Mem. de I'Acad. Iinper. des Sciences de St, PiUersbourg, VII 

 Series, Tome XXXIII, p. 125, pi- 19, figs. 3 a, b- 



