200 W. R. Hiidleston—On the Torhshire Oolites. 



It has been suggested that this shell is a Sptnigera. Since wd 

 cannot see whether there is an opposite row of tubercles, and since 

 a portion of the body-whorl is missing, we may fairly be excused 

 from deciding positively either as to the genus or the sj^ecies. I 

 know of no Spinigera with two keels on the whorls of the spire : 

 hence if it is a Spinigera, it should be called Sp. biarmata. 



Genus Turritella, Lamarck, 1799. 



There seems to have been, on the part of some authors, an indis- 

 position to extend the genus Turritella so far back as the period of 

 the Oolitic rocks, and consequently, since some of Phillips's Jurassic 

 Turritellce were Ceritliice, he apparently came to the conclusion, in 

 the edition of 1875, that they all were. Consequently, in the list of 

 Turritellce at page 258, none are quoted either from the Lias or the 

 Oolites. Yet Tate and Blake quote three species of Turritella from 

 the Yorkshire Lias, all of them forms recognized as Liassic by foreign 

 authors. I think it must be conceded that a small group of shells 

 exists somewhat sparingly in the Dogger, which are also best referred 

 to Turritella. They are elongate, many-whorled, spirally striated, 

 and without longitudinal costae : the whorls are separated by a wide 

 suture, and the aperture, where visible, is rounded and entire. I 

 do not know that any shells fairly referable to Turritella occur in 

 the Yorkshire Oolites higher than the Millepore Rock, where poor 

 specimens, assigned to T. quadrivittata, have been found ; but we note 

 Turritella here and there on several well-known horizons, such as 

 the Callovian of Montreuil Bellay, where the genus is represented 

 by more than one form. Whether these several forms should be 

 classified under the Turritella of Lamarck, may be a fair question. 

 If not, it would be necessary to constitute a new genus to receive 

 them. 



46. — Turritella opalina, Quenstedt, 1858, var. canina. 

 Plate YII. Figs. 9, 9a, 10, 10a. 



1832. Turritella elongata, Zieten. PI. 32, figs. 5, 6. 



1849. Cerithium elongatum, D'Orb. Prod. i. p. 250 (Toarcien). 



1858. Turritella opalina, Quenstedt. Jura, p. 326, pi. 44, fig. 15. 



Bibliography, etc. — Zieten seems to have been the first to point out 

 the occurrence of a fine species of Turritella in the debatable ground 

 between the Lias and the Oolites, but he fixed upon a name already 

 appropriated by Sowerby for a Tertiary fossil not so very dissimilar. 

 Hence Quenstedt's name has the preference, and there is this further 

 advantage, inasmuch as it describes the horizon where his fossil 

 occurs, viz. in the upper part of the Brown Jura, Alpha, which is 

 on a slightly lower horizon than our Dogger : more about the horizon 

 of the Dogger Sands in fact, though we cannot claim its comjDanion, 

 Trigonia navis, as a Yorkshire fossil. 



Description. Section A.~ Specimen from the Dogger (zone 1), 

 Peak (Blue Wyke). Bean Collection, British Museum. Figs. 9, 9a. 



Length restored about 40 millimetres. 



Width lOi „ 



Height of whorl to width 50 ": 100. 



Spiral angle 23°. 



