XATICA. 227 



has assigned it. According to the last-named author it 

 is the N. similis of Koch. Leach named it N. La- 

 mar ckiana. Nerita pellucida and N. alba of Adams (Linn. 

 Trans, iii. p. 67) were possibly the fry of this species. 

 Natica immaculata of Totten is allied to the variety 

 lactea, but has a much more open umbilicus. 



6. N. Montacu'ti*, [Montagui] Forbes. 



-V. Montagui, Forb. Mai. Mon. p. 32, pi. ii. f. 3, 4; F. & H. iii. p. oM 

 pi. ci. f. 3, 4, and (animal) pi. PP. f. 4. 



Body pale brownish-yellow, crearncolour, or whitish with a 

 brownish or Yellowish-brown tint above, whitish underneath : 

 snout very broad, light-brown, and rounded in front: tentacles 

 moderately long and pointed, white; they are sometimes 

 carried nearly erect, or project sideways : eyes, none observable : 

 foot capable of great dilatation, and, when fully extended, 

 occupying twice the area of the shell ; anterior portion divided 

 above into two ear-shaped or triangular lobes, and edged with 

 reddish- or purplish-brown ; middle portion squarish in front, 

 with a slight indentation in the middle and rather sharp 

 corners ; posterior portion oval, with a rounded tail. 



Shell globular, thick and solid, opaque, having very little 

 gloss ; sculpture, none except minute irregular lines of growth : 

 colour fawn of various shades passing into buff or reddish- 

 brown ; there is often a whitish band round the top of each 

 whorl : epidermis yellowish-brown, usually preserved within 

 the umbilicus only : spire short, with a blunt point : whorls 

 5-6, tumid, enlarging more gradually than in JV. Alderi ; the 

 last whorl occupies nine-tenths of the spire : suture nearly 

 straight, wide and narrowly channelled : mouth equal in length 

 to nearly four-fifths of the spire, not much expanded, and 

 bluntly angulated at the base ; throat reddish-brown : outer 

 lip gently incurved on the periphery, having a rather thick 

 edge: inner lip white, irregularly spread over the pillar, 

 forming a small callosity or tooth-like process at the upper 

 angle of the mouth, besides a slight pad in the middle, being 

 the termination of the umbilical ridge, the lower part is very 

 thick: umbilicus rather large and roundish, not much contracted 

 by the inner lip ; it has on that side a strong and wide ridge, 



* Earned in memory of the author of ' Testacea Britannica.' 



