7927 SYSTEMATIC 43 



Feb. 



less cadiconic, with approximate ribbing, slightly arcuate backwards 

 over venter; fibulate ornament in inner whorls. EL = Li>L2, all 

 subcomplex. 



Similar species : Am. crassus ; Meneghini, Pal. Lomb., xvi, 2. 



Athlodactylites, nov. ; G. T., Dactylioceras athleticiim (Simpson), 

 S. B., T.A. PL LIb. Like Orthodadylites with appro.ximate elevated 

 ribs, but they curve forward over the venter ; Whitby, Upper Lias, 

 athleticum. 



Similar species : Barrington, Somerset, Upper Lias, Bed 2 a ; 

 Dactylioceras crassulosnm, (Simpson), T.A. LVIII ; Am. annulatus ; 

 Dumortier, iv, xxvi, 3, 4. 



Simplidactylites, nov. ; G.T., S. simplicicosta, nov., M.P.G. 

 Coll. 38304 ; Harrington, Somerset, Upper Lias ; another example, 

 Barrington, U.L., Bed 22 ; M. P. G. Coll. 38303. Subcadicone passing 

 to serpenticone. Somewhat thick ribs, often simple or undivided, 

 recalling something of Am. ragazzonii, Hauer, (Amm. Medolo; Sitz. d. k. 

 Akad. d. W. math, naturw. CI. xliv (i), 1861, 415 ; \, i6, 17), but 

 with too many divided ribs to allow of any real connection. The ribs 

 of Simplidactylites pass over the venter with a forward sweep ; on sides 

 they are straight without nodes at furcation. 



Similar species : Porpoceras crassiusculum (Simpson), T.A. CCIX ; 



Koinodactylites, nov.; G.T., S.B. Coll., No. 4713; Whitby, 

 Yorkshire, Upper Lias, [.Alum Shale] ; identified with Am. communis, 

 J. Sowerby, M.C. cvii, 2. EL>Li, L2 bident — all lobes short. 



Similar species : Am. angulatus, Sowerby, cvii, i ; Sfephanoceras 

 commune ; Wright, Lxxxiv, i — 3. 



Nomodactylites, nov. ; G.T., Nomod. temperatus, nov., S.B. 

 CoU. No. 4714 ; Whitby. Yorkshire ; Upper Lias [Alum Shale] ; 

 EL > Li, L2 short, subtrident ; identified with Am. communis, 

 J. Sowerby, M.C. cvii, 3, (not 2). Differs from Koinodactylites by 

 stouter habit of growth and longer lobate suture-line. 



Similar species : Am. raquinianus, d'Orbigny, cvi, i, 2. 



Curvidactylites. nov. ; G.T., Curvid. curvlcesta, nov., S.B. 

 Coll. No. 4724 ; Whitby ; Upper Lias, [Alum Shale or Cement Shale]. 

 Like Am. communis. (Koinodactylites) , but with smaller, more numerous 

 ribs, which are slightly curved forward, both laterally and ventrally. 

 EL > Li, L2 unident ; Li and L2 long and slender. 



Similar species : Stephanoceras commune ; Wright, Lxxxiii, 3, 4. 

 This shows similar size of ribs, but they lack the curvature, while its 

 suture-line is of Koinodactylites style. 



Parvidactylites, nov. ; G.T., Parvid. parvus, nov., M.P.G. 

 Coll. No. 38023, Barrington, Somerset, Upper Lias, Bed [26 ?]. Like 

 Zugodactylites, but with feeble and irregularly-spaced nodate ornament — 

 many ribs without nodes — and a feebly-developed suture-line. No sign 

 of any fibulate ornament. EL > Li, L2 broad. 



Mucrodactylites, nov. G.T., Ammonites mttcronatus, d'Orbigny, 

 (Ter. jur. Ceph. ; Pal. fran?., 1845, p. 328 ; civ, 4, 5, 8) ; serpenticone, 

 paucicostate ; bi- (or trifurcate) ; on venter loop-like ribs medianly 

 broken ; EL >> Li ; L2 short, bident, from d'Orbigny's figures. 



Similar species : Am. mucronatus ; Dumortier, iv, xxviii, 3, 4. 



Dactylioceras, Hyatt, 1867. See T.A. i, 1911, p. v. [D. 

 anmdatum, Barrington, Bed 18/19; M.P.G. Coll. 38302; T.A. PI. DCC ; 

 EL > Li ; L2 short, trident]. 



