PLATE XI. 



POTERIOCEEAS ELLIPSOIDEUM, PMlUpS, Sp. (Page 115.) 



Fio. 



1. Ventral view of a specimen containing body- whorl and several chambers ; 1 a, 



lateral view ; 1 b, diagram of section of apical end. Wolborough. Museum 

 of Practical Geology. 



GrOMPHOCERAS POCULDM, n. sp. (Page 117.) 



2. Lateral view of a specimen retaining shell but having no signs of surface 



ornament. The line of the uppermost chamber is perhaps rather too 

 distinctly shown in this drawing, and some crushed shell in the matrix 

 above the upper margin is omitted ; 2 a, front view. Lummaton. My 

 Collection. 



3. Lateral view of another specimen ; 3 a, diagram of section showing position 



of siphuncle. Lummaton. My Collection. 



GoMPHOCERAs, sp. (Page 118.) 



4. Ventral view of a specimen in which the septal part is almost perfect and the 



upper part is broken away and shows the interior of the body-chamber ; 

 4 a, diagram of section showing position of siphuncle. Wolborough. 

 Vicary Collection. 



Phragmoobras ? UNQULATUM, WMdhome. (Page 111.) 



5. Lateral view of a nearly perfect specimen retaining shell; 5 a (lower figure), 



ventral view ; 5 a (upper figure), surface enlarged. Wolborough. Museum 

 of Practical Geology. 



6. Lateral view of a fragment of the dorsal part of another specimen ; 6 a, surface 



enlarged showing the sinus. Wolborough. Museum of Practical Geology. 



7. Lateral view of another specimen, defective ventrally. Wolborough. Museum 



of Practical Geology. 



8. Ventral view of a specimen. Wolborough. Museum of Practical Geology. 



Cyrtoceras Robertsii, n. sp. (Page 109.) 



9. Ventral view of a specimen retaining shell and showing asymmetry ; 9 a, lateral 



view ; 9 ft, diagram of section showing probable position of the siphuncle ; 

 9 c, portion of surface enlarged showing the character of the ornament and 

 the ventral sinus. Lummaton. My Collection. 



