SUPPLEMENT.— ANCOLIOCERAS. xlvii 



IX. Genus — Ancolioceras, 1 S. Buchman. 



(Type — Ancolioceras substriatum, sp. n.) 



Definition. — Platyleptogyral, angustumbilicate ; subdensiseptate, subbrevi-sub- 

 latilobate; laterally subflexiradiate ; peripherally acutanguliradiate, subacuti- 

 fastigate, subalti-nonsepti-carinate. 



Distinction. — From Lioceras, the radial line is straighter laterally and more 

 projected peripherally ; the sutnre-line has shorter lobes ; the carina is more 

 distinctly prominent. From Gypholioceras, the radial line is straighter laterally, 

 scarcely so projected peripherally, and the carina is more 

 distinctly separated. Fm . _ Radial ^ 



Remarks. — This is a third series of Lioceratoids, occur- ot Ancolioceras 



suistriatum. 



ring at a later date than Lioceras or Gypholioceras. From 

 them it is distinguishable by slight differences in the curva- 

 ture of the radial line. Unfortunately the material is scanty, but it is sufficient to 

 indicate that these differences would be associated with another very distinctive 

 feature — an elevated carina. 



The scanty material shows that if the series were complete there woiild be 

 species in three stages of development — tuberculate, costate, costatistriate ; and 

 inferentially in a fourth, striate. 



Although the species of this genus occur at a later date than Lioceras or 

 Gi/plioJioceras, yet one of them indicates an earlier stage of development than is 

 seen in either of those genera — the tuberculate stage. 



1. Ancolioceras carinifertjm, S. Buchman. Suppl., Plate XI, figs. 7 — 9. 



Description. — Subplatyleptogyral, sublatumbilicate, flexi-subcrassi-costate, 

 bullate, subalticarinate. 



Remarks. — The bulla? are placed round the edge of the umbilicus, along the 

 top of the inner margin. A bulla gives rise to two costas, and there is between 

 two groups of bullicostas a single costa, which is obsolete in the area where the 

 others join a bulla. 



Distinction. — The rather strongly elevated nonsepti-carina forms a particular 

 feature separating this shell from other tuberculate species ; and the radial 

 curve must also be considered. 



1 " Ajkos, a bend. 



