106 



Harmotome is one of the rarest of those silicates which are 

 usually found in Trap formations, and generally occurs in macled 

 crystals ; the form is a right rectangular prism. 



At Strontian, in Scotland, it is sometimes found in uncombined 

 crystals ; a figure of one of which is given in Dana's Mineralogy, 

 p. 332; the crystals on this specimen resemble those, and like 

 them, are found coating carbonate of lime. Harmotome may 

 therefore be added to the list of American minerals. 



Mr. Teschemacher also exhibited specimens of a new mineral 

 from the Clifl?' mine on Lake Superior, resembling in many of 

 its properties VoIbortJiite, a Vanadiate of Copper. 



Dr. Gould presented descriptions of the following shells, 

 brought home by the U. S. Exploring Expedition : 



Trochus bicrenatus. Testa pyramidata, flavescens, flam- 

 mulis rufis alternis saturatioribus ornata, lineis equalibus granu- 

 losis cincta : spira anfr. 7-8, pene concavis, ad peripheriam 

 acutis et denticulis roseo-crenulatis ad 15 munitis : basis planu- 

 lata ; vortice umbilicali eburnea : apertura trapezoidea ; colu- 

 mella contorta. Diam. |, alt. f poll. 



The species most resembling it are T. fanhriatus, Lam., afid 

 T. Buschii, Phil. ; but from these and all others, it is well distin- 

 guished by its doubly crenate margin, as viewed from below. 

 The profile outline is a little concave. 



Trochus circumsutus. Testa solida, elevata, accurate conica, 

 imperforata : spira anfr. 9, subangulatis superne declivibus, infra 

 nodis obliquis et liris granosis cinctis : color cinerea, portionibus 

 cavatis saturate olivaceis suturas similantibus : basis planulata sulcis 

 filiformibus concentricis ad 12 insculpta ; regione umbilicali ebur- 

 nea : apertura transversa, sub-rhombea ; columella brevi, acuta, 

 contorta. Lat. -^^, alt. -^^ poll. Hah. Madagascar ? 



In form and sculpture this may be compared with the tip of 

 T. pica. The peculiar coloration, representing courses of olive-" 

 colored stitches is characteristic. 



Trochus spurcus. Testa parva, solida, globoso-conica, nitida, 

 ubique striis volventibus exilibus insculpta, oblique strigis angu- 

 latis stramineis et fuscis alternantibus variegata, prope suturam 

 maculis quadratis quoque picta : spira anfr. 4-5 ventricosis, ' 

 ultimo subangulato ; sutura impressa : basis concavo-conica, im- 



