CKICK : ON STYBACOTFATTHIS ORIENTALIS. 



275 



phragmocone and the surface of the guard. At the anterior part of 

 the specimen, and midway between the two longitudinal grooves, 

 there is a small triangular indentation, which may be the posterior 



T^ s vg 



^l 



\ M 



B 



Sh 



did 



Styracoteitthis orientalis. A, ventral aspect ; B, right lateral aspect ; C, left lateral 

 aspect ; D, dorsal aspect ; E, anterior view of alveolar end ; F, natural trans- 

 verse section of guard, being the posterior view of the anterior half of the 

 specimen. Eocene : Sharkeeyab, Oman, Arabia. Drawn of the natural size 

 from the type-specimen in the British Museum (Natural History). [C. 8010.] 

 ig. incised groove. 

 s. indentation at middle of anterior end of ventral surface. 

 si. siphuncle. 

 di.d. dorso-lateral depression. 



termination of another gi'oove that was continued forwards over 

 a portion of the alveolar cavity that is not now preserved. The 

 surface of the specimen is roughened, having in places, especially at 



