. The Geology of Minnesota . of two layers, the inner nacrous. Surface of specimens markedby more or less obscure lines of growth. These are usually the strongest on the dor-sum, where they may be seen also on some casts of the interior. The latter, however,are in most cases quite smooth and without a trace of markings. Externallayer of shell not seen in good condition, so we cannot say positively, thoughwe suspect it to be so, that it was marked near the umbilicus, as in the followingspecies, by fine granulose striee. Hight of shell mm.; median hight of mm.; width of same 19
. The Geology of Minnesota . of two layers, the inner nacrous. Surface of specimens markedby more or less obscure lines of growth. These are usually the strongest on the dor-sum, where they may be seen also on some casts of the interior. The latter, however,are in most cases quite smooth and without a trace of markings. Externallayer of shell not seen in good condition, so we cannot say positively, thoughwe suspect it to be so, that it was marked near the umbilicus, as in the followingspecies, by fine granulose striee. Hight of shell mm.; median hight of mm.; width of same 19 mm.; width of inner volution 7 mm.; depth of sinus 8 two other specimens, one very large, these dimensions are respectively, 24,10, 23,7 and 9 mm., and 30; , 27, 8 and 12 mm. This species is often met with in collections under the name of Bellerophonhilobatus, but it is really quite distinct, as anyone may see by comparing theaccom^janying figures of that species with those of B. rectangular is given on
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Keywords: ., bookcentury1800, bookdecade1890, bookidgeologyofmin, bookyear1897
