ALARIA. 115 



— mostly from P : (page 31). Specimens showing any of the processes (6 c, 6 d) 

 are rare. The specimen 6 d differs somewhat from all the others, and approaches 

 the var. Phillipsii in some respects, and still more reminds me of the form provi- 

 sionally described as Al. spinidosa. I think that Al. hamus, as defined above, is 

 mainly confined to the upper division of the Inferior Oolite, at any rate in Dorset- 

 shire. Elsewhere in England, except perhaps at Dundry, it appears to be represented 

 either by the variety Phillipsii, or else by dwarf forms, like those to which I now 

 direct attention. 



33. Dwarf varieties op Alaria hamos. Plate IV, figs. 7 a, 7 b, 7 c. 



Specimens from the Parkinsoni-zone of Notgrove (fig. 7 a) and from the Parlcin- 

 soni-zone of Horton Hill (Upper Trigonia-grit) are fairly similar. The dwarfing 

 extends to all the whorls, the whole shell is proportionally smaller, and the large 

 spirals on the anterior portions of the whorls are always three in number. The keel of 

 the body- whorl possesses the spinous lumps characteristic of Al. hamus, but they are 

 better shown in specimens from Horton Hill than in the more slender ones from 

 Notgrove, which might indeed be regarded with equal justice as dwarfs of the 

 variety Phillipsii. 



The specimen from Horton Hill (fig. 7 b) is sufficiently well preserved to 

 show that it was possessed of a wing and " tail " in all respects, except as to size, 

 identical with Al. hamus. The evidence of a wing in the case of the Notgrove 

 specimens is less clear, bat the plain and strongly-keeled body- whorls show that 

 the specimens are mature shells. 



The specimen (fig 7 a) from the Gryphite-grit of the neighbourhood of Stroud 

 presents other differences. The shell is shorter in proportion to its width, and 

 seems to have matured earlier ; the whorls are strongly muricated. In this speci- 

 men the three spirals which occupy the anterior portion of the whorls of the spire 

 are so conspicuous that, if a trivial name be required, I would suggest that of 



TRICTNCTA. 



The specimen (fig. 11), also from the Gryphite-grit, is most probably an imma- 

 ture form of Al. Phillipsii. Such forms are not uncommon in the Scarborough 

 Limestone, and these of course are referred to Al. Phillipsii in default of better 

 evidence. 



It should be noted that, while the full-grown and typical forms of Al. hamus 

 occur in the Dorset district, these dwarfed varieties seem to take its place in the 

 Cotteswolds. 



