LEBOUR : VARIATION [iN RADUL.Ii] OF BUCCINID.E. 285 



Centrals. Laterals. Number of Specimens. 



Left. Right. 



2-33- 

 4 - 3 3 . - 



1 - 3 3 



3 - 4 3 - 2 (i ?, I (J). 



3-34- 



3 - 36 



2 - 4 3 

 2-34- 

 3-54- 



3 - 3 3 - 



. (1 bilobed). 



In eight specimens, all female, from Berwick-on-Tweed, four were 

 normal, the others varied thus : — 



Centrals. Laterals. Number of Specimens. 



5-3-2 

 2 - 3 - ,1 



(1 bilobed). 



4-3-1 



We see from these tables that although about 43 per cent, are 

 normal, yet there is reall}' more variation in this species than m 

 Bucciiuim tmdatum, for if we counted as normal those specimens of 

 Bticcimim which have seven centrals, there would be a much smaller 

 per-centage of variations. There may be as many as five centrals and 

 as few as one in Neptunea afitiqua, and there may be six laterals, but 

 I have not found less than three. The same tendency to multiply 

 lobes is found in this species, and although most are regular through- 

 out, yet one shows a curious irregularity (fig. 6) ; it is normal all 

 through except one tooth, which bears two minute extra lobes. 

 Another (fig. 11) has very irregular laterals on the right side, near 

 the front they are almost normal, with a small extra lobe, but gradu- 

 ally become monstrous with six irregular teeth. So far as can be 

 seen from so few examples, the side variations are about equally 

 distributed on the left and right side. 



Ten specimens of Volutopsis tiorvegiais \\trQ examined. These 

 were obtained with Bucciniiin uiidatum and Neptimea antiqua from 

 the North Sea, 120-130 miles E. by N. of the river Tyne. There 

 were eight female and two male ; seven females were alike in the 

 radula, having two teeth to each lateral plate and four to the central. 

 This we may suppose to be the typical form. One female and two 

 males had five centrals, and one male had a small accessory tooth 

 between the two normal teeth of the right lateral plate, and a bilobed 

 fourth central on the left side, thus showing a tendency to increase 

 the number of teeth, as in Buccinum and Neptunea, 



