902 THE PALEONTOLOGY OF MINNESOTA. 



[Salpiugostoma sculptilis. 



SALPINGOSTOMA SCULPTILIS, n. sp. 



PLATE LXXXII, FIGS. 16-20. 



Shell scarcely attaining medium bight, consisting of at least three and one-half 

 volutions, the hight, including apertural expansion, about 40 mm. Inner volutions 

 enlarging very slowly, somewhat rhomboidal in section, obtusely angular on the 

 dorsum and more narrowly angular on the sides, the hight and width respectively 

 as six is to ten. Aperture expanding abruptly till it measures at least 30 mm. in 

 width and 28 mm. in hight; anterior sinus very shallow. Umbilicus large, exposing 

 all the whorls. Surface markings forming a coarse network of alternating hex- 

 agonal meshes; an extra thread passes in an obliquely forward and inward direction 

 through each mesh. In the umbilicus the oblique thread is the most conspicuous. 

 About six rows of meshes occur on the small part of the outer volution on each side 

 between the slit-band and the lateral edges. On the apertural expansion the 

 markings increase in strength, though numerous longitudinal threads are interpo- 

 lated as the space to be covered grows larger. Dorsal fissure about 17 mm. long. 



This species may be related to S. expansa Hall sp., but it is readily distinguished 

 by its smaller size and by the angularity of the back of its inner volutions, these 

 being more rounded in that species (i. e. elliptical or reniform in section). The 

 dorso-ventral diameter of the aperture also is relatively less in that species. The 

 surface ornamentation of S. expansa being as yet unknown, we cannot say how it 

 compares with that of S. sculptilis. Compared with S. buelli W bitfield, it will be 

 found that S. sculptilis is smaller, has different surface markings, and volutions that 

 are not only narrower but rhomboidal instead of reniform in section. 



Formation and locality. Four specimens, all from the Fusispira bed of the Trenton group, three 

 from different localities in Goodhue county, and one from Ollie Hansen's farm near Fountain, Minnesota. 



Colkrtions. Geological and Natural History Survey of Minnesota; E. O. Ulrich; W. H. Scolldd. 

 Museum Register, No. 7462. 



SALPINGOSTOMA IMBUICATA, n. sp. 



PLATE LXXXII. FIGS. 21 and 22. 



Of this species we have but a single imperfect cast, the greater part of the 

 expanded aperture being broken away. In the remaining parts it resembles S. 

 sculptilis but the whorls are even narrower, the hight being to the width as five is 

 to six and the section broadly subelliptical. The back of the volutions is broadly 

 convex, the sides narrowly rounded or subangular, and the umbilical or ventral 

 slope slightly flattened. The dorsal slit seems to have been at least 30 mm. in 

 length. The shell is entirely gone except in the umbilicus, where, in the suture 

 lines especially, there are remains of very regularly recurring, salient, thin, trans- 



