382 



Gros Cap, where slates are found intercalated between granite 

 and gneiss rocks. 



Farther west, in the Black Hiils of Nebraska, Dr. Hayden 

 has recognized the Primordial fauna in a series of sandstone rocks, 

 resting on slates, mica-schists, and azoic rocks. Dr. Ferdinand 

 Roemer, in his exploration of Texas (" Die KreideUldungen von 

 Texas und Hire organisclien Einschlilsse " Bonn, 1852), has de- 

 scribed trilobites from the San Sabaz, which M. Barrande refers 

 to the Primordial fauna ; and Dr. B. F. Shumard has since discov- 

 ered in the same region of Texas, trilobites of the genus Arionel- 

 lus, Lingulce, Obolus, and Ortkis, which leave no doubt of the 

 existence of the Taconic system in Texas (" Trans, of the Acad, of 

 St. Louis,'' p. 673, 1860). Even from the small notice of Dr. 

 Shumard, it appears that the Primordial fauna of Texas is almost 

 identical with the one just discovered in the Cantabrian Chain of 

 Spain by Casiano de Prado, {^\Bull. de la Soc. Geol. de France,'' p. 

 516,vol. XVIL, 1860). 



Dr. A. A. Gould presented the following descriptions of 

 new shells collected by the North Pacific Exploring Ex- 

 pedition : — 



Mangelia semiassa. T. rhomboideo-fusiformis, crassa, nitida, 

 albida antice livida, 8-plicata et striis exilissimis volventibus 

 insculpta ; anfr. 6 angulatis ; sutura impressa : apertura ^ totius 

 longitudinis, pyriformis, antice acuminata-; labro simplici incras- 

 sato ; sinu vix notato ; columella recta, Uvida. Axis 8 ; diam. 

 3 millim. Inhabits ? 



Mangelia tetragona. T. acicularis, turrita, quadrangu- 

 laris, (angulis compressis),lactea, striis subtilissimis confertis trans- 

 versis insculpta ; anfr. 6 pyramidatis, apicali mamillato : apertura 

 4- totius longitudinis, satis ampla ; labro incrassato postice angu- 

 lato. Axis 6 ; diam. 2 millim. Inhabits China Seas. W. S. 



Mangelia concinna. T. tenuis, elongato-ovata, turrita, ni- 

 tida, striis exilissimis transversis insculpta, straminea maculis 

 quadratis ferrugineis juxta suturam, deinde vitta angusta alba, 

 denique fasciis et lineis rufescentibus picta ; anfr. 8 postice decli- 

 vibus, supernis strigatis : apertura ^ totius longitudinis, angusta ; 



