8gb YORKSHIRE TYPE AMMONITES— II Nov. 



89. AMMONITES CRASSOIDES, Simpson 

 (Plate LXXXIX) 



Original Description 

 " 62. A[mmonites] crassoides. [M. Simpson, 1855, P- 55-] 



[" The following species, to the end of the Section, have all a family 

 resemblance to A. communis : — Whorls narrow, exposed, with numerous 

 slender, annular ribs, which generally split in two on the back." p. 50.] 



" This is still thicker in proportion [than A. crassus, Y. and B.], 

 the inner whorls are rather concealed, and there is a row of tubercles 

 in the middle of the whorls ; the aperture is transverse, and it is altogether 

 a more elegant species than the last. — Jet-rock, U.L." 



Simpson, 1884, 86, the same. 



Remarks 



Proportions, 76, 25, 36, 52 ; substeno-, pachygyral, subextremi- 

 latumbilicate. 



Stages, conch, somewhat cadicone, passing to serpenticone ; periphery, 

 1 ; ornament, 5*. 



Ornament, tuberculate stage catagenetic, it appears to be regular 

 in inner whorls, is intermittent and then failing on outer one. As inner 

 whorls are damaged, it is uncertain if there be fibulation ; but comparison 

 with Wright, 1884, lxxxv, 2, 3, suggests its presence. Ribs septate, 

 bifurcate and entire ribs more or less alternating. 



Genus, Coeloceras, Hyatt ; family Dactyloidae. 



Result 

 Cceloceras crassoides, Simpson sp. 1855, Whitbian, exaratum zone, 

 Whitbv. 



