298 ME. s. s. BUCKMAif OX [vol. Ixxiii, 



Table XV. — Proportions : Ahieiites 

 [brooki and tvugescexs Series). 



rii (D 



rF.ii4, 



LT.llO, 



22, 

 22-5, 



20, 



20, 



57. 



F. 97, 



26, 



25-5, 



53. 



F. 79, 

 F. 65, 



32, 



31, 



[26], 

 26, 



46. 

 46. 



S. 53, 



34, 



26?, 



40? 



F. 92, 



rF.142, 

 T.140, 

 F.147, 

 F.148, 



37, 

 37, 

 39, 

 36, 



40? 



27, 



28' 

 27, 



34. 

 34. 



35! 

 35. 



S. 171, 



33, 



32, 



45. 



"F. 53, 



- F.118, 



T.115, 



35, 

 37, 

 35, 



35, 

 34, 

 33, 



42. 

 37. 



fArietites aff. plotti (Eeynes). 



{Ar. honnardii Wright, xi, p. 287).'^ 



Arietites plotti (Eeynes). 



(Ain. plotti^ejnes, xxxvi, 15, 16).- 



Arietites turneri (J. de C. Sowerby). 



(Ammonites turneri Sowerby, 



_ cccclii, top fig.)."* 



§ "g ^ {Am. turneri Eeynes, xl, 18, 19).^ 

 Arietites sp. 



{Arietites sp. Laug, from. Bed 77)."* 

 Arietites hroolci (J. Sowerby). 



{Ammonites hroolci Wright, ii, 5) ^. 

 {Aw.. hrooM Wright, ri, 4, p. 280)'^ 



{Ain. hrooki Reynes, xxxYii, 5, 6).^ 

 (^ {Am. hroolti Sowerby, cxc)"* 



Arietites turgescens, nov.^ 



Arietites aff. turgescens. 

 gijg |_ {Ar. turneri Wright, xii, 1-3)'^ ... 



Genus Aexioceeas Hyatt. 

 Aexioceeas flatum, nom. nov. (PI. XXXI, figs. 2a & 2 h.) 



1878. Arietites semicostatus Wright (noii Young & J^ird sp.), 'Lias Ammonites 

 pi. i, fig. 7 only. 



Description. — Subpla ty- subleptogyral ; subextremila tumbili- 

 cate; periphery fastigate, distincti-carinate ; whorls smooth ; suture- 

 line simple, external lobe about as long as superior lateral. 



Remarks. — A smooth, keeled Arnioceras, possibly adult. 

 Arnioeerates in the smooth stage have been made types of five 

 species, and names of other species have been applied to them. For 

 consideration now are — 



1. 1858, Ammonites miserahilis Quenstedt. 



2. 1867, Psiloceras acutidorsale Hyatt. 



3. 1867, Arnioceras cuneiforme Hyatt. 



4. 1876, Mgoceras nigrum, Blake. 



5. 1878, Arietites semicostatus Wright {non Yoimg & Bird sp.). 



6. 1883, A')nm,onites falcaries Ixvissimus Quenstedt. 



The species now described, however, agrees only with Wright's, 

 judging his figure as depicting a keel, for Hyatt's and Blake's species 

 are both ruled out by their peripheries. Psiloceras acutidorsale 

 has 'abdomen prominent, acute," — no mention of a distinct keel ; 

 Blake's ^y<9C(?r«s nigrum has an 'angular front'; and Hyatt's 

 Arnioceras cuneiforme is figured with merely a sharply angulate 

 periphery ; Ammonites falcaries Icevissimus is different in pro- 

 portions, so there remains only A. miserahilis, which Quenstedt 



^ ' Monogr. Lias Ammonites.' '-^ ' Mon. Amm.' 1879. 



^ ' Mineral Conchology.' ■* See Chronological paper, p. 271. 



^ Proc. Cotteswold F. C. vol. iii, 1864. ^ Where the keel ends. 



