196 BULLETIN OF THE NATURAL HISTORY SOCIETY. 



Fig. G. Platycerds cymbula, n. sp. a Side view; — b Seen from above. 

 Mag. f. See p. 191. 



Fig. 7. Modiolopsis thecoides, n. sp. a Interior of the right valve; — 

 b Section near the hinge ; — c Section near the posterior 

 end. All mag. \. See p. 191. 



Fig. 8. Urotheca pervetus, n. sp. Distal part of the tube. Nat. 

 size. See p. 192. 



Fig 9. Hyolithellus flexuosus, n. sp. Proximal end of the tube. 

 Mag. -f- Seep. 192. 



Plate II. 



Fig. 1. Hyolithellus micans, Bill, a A group of paired tubes; — b 

 Another group ; — c A third group, all mag. • \—d Groups 

 . of the tubes in association with Orthotheca bayonet. Nat. 

 size. See p. 192. 



Fig. 2. C oleoides typicalis, Walcott. Part of a tube. Mag. 1 1 ". See 

 p. 192. 



Fig. 3. Orthotheca stiletto, n. sp. a The tube ; — b Section at the 

 aperture, both mag. \. See p. 193. 



Fig. 4. Orthotheca j)U(/io, n. sp. a A tube decollated ; — b Form of 

 aperture ; — c Section at the decollation; — d A smaller ex- 

 ample, side view; — e An operculum, possibly of this species. 

 All mag, |. See p. 193. 



Fig. 5. Orthotheca sica, n. sp. a Decollated tube, ventral side : 



b Form aperture ; — c Another tube with more rounded 

 angles; — d Form of the aperture. All mag. ~ ; — e An 

 operculum, possibly of this species. Mag. |. See p. 193. 



Fig. G Orthotheca sica, quadricostate mutation ; a Ventral view of 

 the tube; — b Section at the aperture. Both mag. - r 

 Seep. 193. 



Fig. 7. Ifeleniagranulata, n. sp ; a Side view of the tube ; -b Front 

 view of another tube. Both mag. 'j ; — c Section of the 

 second tube. Mag. \ ; — d Large end of a tube, mag. '\ : 

 — e Section, mag. {. See p. 192. 



