202 HELICERAS, BELEMNITELLA, ETC. 



Sectifm 1. Ac(eli, Bronn. Rostrum without dorsal or ventral grooves 

 at its anterior end. 



Subsection 1. Acuarii, Orb. Rostrum more or less conical, with- 

 out lateral furrows, but often channeled at the i)Osterior end. 

 Jura., Chalk. 20 species. 



Subsectioti 3. Clavati, Orb. Shell lengthened, with lateral fur- 

 rows. Lias., 3 species. 

 Section II. Gastrocceli, Orb. Rostrum with an anterior ventral 

 groove. 



Subsections. Canalictdati, Orb. Rostrum without lateral grooves. 

 Jura., 5 species. 



Subsection 4. Hastati, Orb. With two long lateral grooves. 

 Jura., Chalk, 19 species. 

 Section III. Notocceli, Orb. With a deep dorsal groove. 



Subsection 5. Dilatati, Orb. With lateral grooves. Neocomian, 

 9 species. 



B. EXCENTRTCUS. PI. 9.5. fio". 4f)ii. Oxford. Oolite of England. 



B. SEMIHASTATUS. PI. 1»5, flgs. 4r)(), 457. Jurassic, of Wurlemburg. 



B. SEM1HASTATU8. Phragniocoiic ; view of sijjlioiial side (fig. 457). 



(4Lnus HELICERAS, Dana. 



a. FuGiENSis, Dana. PI. 95, fig. 458. In slate rock. Gape 

 Horn. Only species. 



Genus BELEMNITELLA, rrOi-l.. 



Six species are found in the upper greensand and chalk of 

 Europe and North America. 



B. MUORONATA, Sowb. PI. 95, fig. 459. jJfae.strichL 



Genus XIPHOTEUTHIS. Hu.vlev. 



Pounded on a single English liassic species. 

 X. ELONGATA, De la Beche. fl. 95, fig. 460. Lyme Regis. 



Genus ACANTHOTEUTHIS, Wagner. 



Oolitic. Seventeen species. 



A. ANTiQUUS, Cunnington. PL 95, fig. 461. Oxford clay of 

 Wiltshire, Eng. 



