E. Wilson — British Liassic Gasteropoda. 259 



encircles the whorl a little in front of the suture, between which 

 there is a narrow raised encircling band ; the aperture is, unfortunately, 

 not well shown ; it occupies five-sixths of the length of the last 

 whorl, the anterior extremity is acutely angulated, with thickened 

 margins, and there is a distinct spiral fold on the columellar border 

 anteriorly. The shelly matter has disappeared, but the surface 

 appears to have been originally smooth. 



Dimensions. — Length, 11 '5 millimetres ; diameter, 5*75 mm. ; 

 length of last whorl, 10 mm. 



Geological Position and Locality. — Middle Lias, Marlstone Kock, 

 zone of Am. spinatus, East Norton Embankment, derived from Tilton, 

 Leicestershire. 



British Liassio Alaki^. 



It has often been supposed that the section of winged shells 

 Ajjorrhaidce, and genus termed Alaria by Lycett, but more clearly 

 defined by Piette, did not appear in the British area until the 

 commencement of the Oolitic period. This is certainly a mistake. 

 Although extremely rare in the Lias, there are undoubted instances 

 of the occurrence of Alariie even in the Lower division of that 

 formation. Messrs. Tate and Blake do not record this genus from 

 the Yorkshire Lias. In his valuable " Contributions to the Paleon- 

 tology of the Yorkshire Oolites," Mr. W. H. Hudleston, F.R.S., 

 referring sj)ecially to the Yorkshire area, observes that " It was in 

 the Lower Oolite that the genus Alaria first began to flourish, and 

 we find that it became tolerably well represented as low down as the 

 Inferior Oolite or Bajocian subdivision " (Geol. Mag. Dec. III. Vol. I. 

 p. 145, 1884). In the year 1867 the late Charles Moore described 

 three species of Alaria from the Upper Lias of Somersetshire, viz. 

 A. unispinosa, Moore ; A. coronata, Moore, and A. angulata, Moore. 

 The first of these certainly, and the last two probably, are true 

 Alari(s. Since then other examples of this genus have been found 

 in difierent portions of the English Lias. Mr. T. Beesley, E.C.S., 

 whose valuable labours in the Lias of Oxfordshire are widely known, 

 informs me that he has obtained the moulds of two AlaricB, which he 

 takes to be A. coronata and A. angulata, from the Upper Lias shales 

 (lower portion of zone of Am. communis ?) of Bloxham, Oxon. Mr. 

 E. A. Walford, F.G.S., of Banbury, records an Alaria {A. unispinosa, 

 query A. semicostulata) from the Upper Lias of Chipping Warden, 

 Northamptonshire. Mr. B. Thompson, F.G.S., has shown me 

 imperfect specimens of an Alaria, which may be A. unispinosa, from 

 the Upper Lias (zone of Am. serpentinus) of Alderton, Gloucester- 

 shire, and Mr. W. D. Crick has recently forwarded me specimens 

 from the Upper Lias of Chipping Warden, and of Burrow Hill, 

 Dodford, Northamptonshire, which are very closely allied, if not, 

 indeed, identical with A. semicostulata, Piet. et Eug. Desl. Last 

 year I had myself the good fortune to find a single well-marked 

 example of this genus in the Lower Lias of Bitton, near Bristol, 

 Gloucestershire. 



In his classical paper on "Abnormal Secondary Deposits in the 



