2 (> '2 HKI.ICKi: \S. Ill I.KMMTKU.A. ETC. 



Section I. ACOOLI, IJronn. Host rum without dorsal or y entral grooves 



at its anterior end. 

 Subsection 1. Acuarn, Orb. Rostrum more or le>s conical, with- 



out lateral furrows. Imt often channeled at the posterior end. 



.lura., Chalk. 20 speci.^. 

 Subsection 2. Clarati, ( )ib. Sliell lengthened, with lateral t'ur- 



rous. Lias.. :! species. 

 Section II. <;ASTROC<KLI, Orb. Kostrum with an anterior ventral 



groove. 

 Subsection 3. Canalicult/ti, < )rl. Host ruin without lateral grooves. 



Jura., 5 species. 

 Subsection 4. flastati, Orb. With two long lateral groove^. 



Jura., Chalk, 111 specie^. 

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



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



9 species. 



I). KXcKNTRicrs. PI. ll.". tio 1 . \^. Oxford. Oolite of Kn 



\\. SK.MIH.\ST ATI s. I'l. '.;"). ti.ii's. 4.">C.. 4.">T. -I urnssic of WnHrntlm ry. 



B. SKMIII ASTATTS. I * h mii'iiMM-oiir : vii-w of si|)ii<ii:il side (lio-. ^.-,7 j. 



(irniis HELICERAS, Diina. 



H. FI(.IK.\>IS. Dana. IM. I)."), lio-. 4a8. In slate 1'ock. ( 

 Horn. Onlv species. 



Genus BELEMNITELLA, rOH,. 



Six species are found in tin- upper pvrnsMiid and chalk of 

 Kui-ope and Xoilh . \nierica. 



H. MI < -KONATA. S<>\\ h. PI. '.:. li--. I.MJ. Md<:</rt<-h/. 



Gtenua XIPHOTEUTHIS. Hiixl.-v. 

 I-'onnded on a sino-| ( . Knrlj s h liassic >peci 

 -\. BLONQATA, \>c la P>eche. PI. !i;. MO-. 4C.O. 



(iei.iis ACANTHOTEUTHIS, 

 ( )o|it ie. Se\-eilteen specie-^. 



A. ANTIQUTJS, Ciiiininutoii. PI. '">. li-. 4f>l. Oxford clay of 

 Wiltshire, EU<I. 



