1926 SYSTEMATIC 4J 



Dactvlioceratid.e. Generic names in use for this family have 

 long been known as unsatisfactory. Now a series of specimens from 

 the Upper Lias of Barrington, Somerset, gives the opportunity to put 

 them on a surer basis. These specimens are superior for the purpose 

 to those coming from Whitby ; because they were carefully collected by 

 Mr. A. Templeman, bed by bed, and almost inch by inch, whereas the 

 Whitby specimens are only known generally as from Upper Lias, though 

 in a few cases there may be three or four smaller divisions — Grey Shales, 

 Jet Rock and so on ; but these do not compare with some twenty-six 

 divisions of Mr. Templeman for Barrington Upper Lias. Then the 

 Barrington specimens show good suture-lines, whereas, in Whitby 

 specimens, too often the suture-lines cannot be seen, or if shown are 

 difficult to mark on the black matrix. 



In the following short generic diagnoses the phrase EL = Li does 

 not here refer to the actual length of the lobes, but is to be read in 

 reference to the guide-line — that the external lobe (EL) and the superior 

 lateral lobe (Li) both come down to the guide-Une. So EL < Li means 

 that Lr comes below the guide-line issuing from end of EL ; and 

 EL > Li, that EL is longer than Li, so far as guide-line is concerned, 

 Li not reaching to guide-hne ; then EL > > Li or EL < < Li means 

 much longer or much shorter respectively. The phrase ' similar species ' 

 indicates those which may be compared to the genotype species, but 

 are not necessarily congeneric — so many forms being figured without 

 suture-line. Cited species having the same trivial name as the genotype 

 are not necessarily conspecific with it. 



For the beds of the Barrington Upper Lias, see S. Buckman, 

 Jurassic Chronology ; Q.J.G.S. Ixxviii (1922), pp. 449 et seqq. 



Kryptodactylites, nov. ; G. T., S.B. Coll. No. 463, Whitby, 

 Yorkshire, Upper Lias [Grey Shales], identified with Am. semicelatus, 

 Simpson, T.A. XXXL 1911. 



SI. somewhat florid, EL = Li, L2 long and aux. i well developed. 

 Oligogyral, parvicostate, without nodes. Similar species : Am. cequi- 

 striatus, Zieten, 1831, xii, 5 ; Am. communis ; Quenstedt, 1885, XLVi, i, 2. 



Tenuidactylites, nov. ; G. T., S.B. Coll. 4712, identified with 

 Am. tenuicostatus, Young & Bird, 1822, xii, 8 ; cf. Daciylioceras' tenui- 

 costatum, T.A., 1920, CLVII. 



Polygyral, parvulicostate.some ribs entire, versiradiate, parvulinodate, 

 ribs slightly arciate over venter ; EL > Li, L2 unident ; Li short and 

 broad. Septate costee with thick septum raising ribs above cast. 



Yorkshire, Upf)er Lias [Grey Shales]. 



Similar species : Am. anniilatus ; d'Orbigny, Lxxvi, i, 2 ; Stephano- 

 ceras anniilaliim ; Wright, Lxxxiv, 7-9. 



Xeinodactylites, nov. ; G. T. Museum of Practical Geology 

 Coll., No. 38013 ; Barrington, Upper Lias, Bed 6, identified with 

 Dactylioceras helianthoides , Yokoyama, 1904, iv, 4-6. 



EL > Li ; L2 narrow, trident. 



Similar species : Coeloceras marioni, Lissajous, igo6, in, 4. 



Anguidactylites, nov. ; G. T., A. anguitormis, nov., M.P.G. Coll. 

 No. 38014 ; Barrington, Upper Lias, Bed No. 11 ; somewhat between 

 Am. raristriatus, Quenstedt 1885, XLVi, 4 and 6, in ribbing, also hke 

 Nautilus anguinus, Reinecke, but more prominent ribbing [finer-ribbed 

 forms possible] ; polygyral, multi-subparvicostate, ribs straight over 

 gibbous venter ; EL nearly = Li, L2 long, narrow, subtrident. 



Similar species : Coeloceras (Dactylioceras) anguinum ; Hug, 1898, 

 VI, 2. 



