118 PLIOCENE MOLLUSCA. 



in the one case and absent in the other, There is a form, moreover, very common 

 at Oakley, that I propose to call var. oalieyensis, which more closely connects the 

 two groups, the specimens shown in my figs. 7, 8, 10 and 15 approaching in spiral 

 sculpture both the Boy ton shell, P. tefragoiia (fig. G), and an Antwerp specimen of 

 var. imhrlcata (fig. 9). A constant feature of the variety oalilei/ensis is the occurrence, 

 especially on the body-whorl, of strong varices, as in Wood's variety elongata ; it 

 is never elongate, however, the body-whorl is tumid and larger than the others, 

 the mouth is wide and the outer lip expanded ; it is very common at Oakley, less 

 so in the Newbournian and Butleyan Crag and unknown from the Icenian. 



At the Newbournian stage a shell, var. uewhimrniensis (figs. IG, 17), appears in 

 the Crag for the first time, being very characteristic of that horizon ; I have 

 dredged similar living specimens off Yarmouth. The variety coiinecfeiis (fig. 2), 

 however, seems intermediate between newhourniensis and incrassata. 



The prevalent form at Butley, var. hiifleijeiisis (fig. 20), approaches a variety of 

 the Recent shell ; it is shorter in the spire, the whorls are less convex, the suture is 

 not so deep, and the outer lip is not thickened. 



The typical variety of the Recent P. lapillns, var. vulijaris, S. V. Wood (fig. 21), 

 a strong conical shell with flattened whorls, and an outer lip thickened internally 

 and bevelled off to a thin edge (fig. 22), is not known to me from any part of the 

 Red Crag older than that of Butley and Bawdsey where it is by no means frequent. 



This form also occurs in the Norwich Crag, although someAvhat rarely, but it 

 is common in the Pleistocene deposits, as, for example, in the March gravels 

 (fig. 23) and the raised beach at Portland. 



Specimens I have received from Bergen, Trondhjem and Denmark (fig. 12), as 

 well as those from the Pleistocene deposits of Christiania figured by Prof. Br^gger 

 and by Prof. Gr. 0. kSars from the arctic shores of Norway, are more or less of this 

 type. The latter authority states that they range in circumpolar latitudes from 

 Scandinavia to Iceland and Greenland, occurring also in Beliring Sea. 



The Purpuras described by Gould from Massachusetts (fig. 11) also approach 

 those of the later zones of the English Crag ; on the contrary, all those I have 

 seen from the Scaldisien of Belgium are of the older or Waltonian type. Nyst 

 represents three forms only from Antwerp: P. fetragona and the varieties incrai<- 

 sata and ii)ihricata of P. lapillns. Dr. Lorie figures the first-named from the Scal- 

 disien of the Dutch borings ; the Butley variety of P. lapillns he gives only from 

 the later Amstelien deposits. 



In vol. iii, p. 90, of the ' Cambridge Natural History,' the Rev. A. H. Cooke 

 figures many specimens of P. lapillns, illustrating the fact, to which he calls 

 attention, that this species is exceedingly variable, and he has kindly sent me for 

 examination a number of them from different localities from his own collection. 

 None of these, however, resemble the special type of Purpura from the Waltonian 

 Crag, nor does he know any Recent shells identical with the latter. The fact that 



