PLATE XXL 



MURCHISONIA DESIDERATA. 

 )'»gre 89. 



Figiii. 1, 2. Anterior aiul posterior views of a sjiecitnen with incomplete spire and imperfect aperture. 



Fig. 3. An enlai-gement of part of a single volution, showing the character of the strise and peripheral band. 



MuEcnisoNiA Leda. 



Fig. 4. An imi)erfect specimen of this species, showing the mouth. 



Mdechisonia Maia. 



Piigo 91. 

 Figs. 8, 7, 8. Imiiei-fect indiviiluals of the species. 

 Figs. 8, 9. Enlargements of a single volution, showing the character of stria" and in'ripbcral hand. . 



Mdrchisonia desiderata var. 



Page 90. 

 Fig. 10. A cast from a mold in silica, giving a somewhat more slender form than the typical specimen. 



MURCHISONIA MICULA. 

 I'agc 93. 

 Fig. 11. A specimen imperfect at the apex (a common condition of the species), enlarged to six diametei-s. 



PlECEOTOM ARIA ? APICIALI8. 



Page 88. 

 Fig. 12. View of the spii-e of a s))ecimen as obtained by a gutta-pei-cha ca.st taken from the natural mol<i ; 

 enlarged to two diameters. 



Pleurotomaria trilix. 



Page 79. 

 Fig. 13. Enlargement of a sjiecimen of this species. 

 Fig. 14. An enlargement of a specimen to two diameters. From the soft shales of the Hamilton group, 



outlet of Crooked Lake, N. Y. 

 Kg. 15. Enlargement of the typical specimen to two diametei-s ; the upper volutions ai-e impei'feet. From 



the shales of the Hamilton group, Senecji Lake, N, Y. 



Pleurotomaria adjutor. 



Page 80. 

 Pig. 16. A specimen of this species (natural size). From the limestone of the Upper Helderberg group, 

 Dublin, Ohio. 



Plecrotomaria insolita. 



Pago 81. 

 Kg. 17. The only specimen of this species known, enlarged to three diametei-s, and showing the character 

 of the sui-face. 



