350 NASSID^. 



being 10 on the body-whorl (besides the basal ridges), 4 on the 

 penultimate and antepenultimate, and 3 on each of the preced- 

 ing whorls ; the aj)ical whorls are quite smooth and lustrous ; the 

 basal portion is smaller, and has only three or four ridges ; the 

 ribs being much more prominent than the striae, the lower 

 half of the shell never displays the tubercular or cancellated 

 appearance of the other species, although the upper whorls in 

 this are somewhat nodulous ; the surface is microscopically 

 marked with close-set longitudinal lines and a few less dis- 

 tinct spiral lines : colour purplish on a yellowish-white ground, 

 with the ribs of the latter hue ; the purple bands and lines are 

 brighter in this species, the lines being from two to three in 

 number : epidermis inconspicuous, or obscured by an earthy in- 

 crustation : spire turreted : ivhorls flattened ; apex more glo- 

 bular than in the last species : suture deeper : mouth propor- 

 tionally larger : canal not so abruptly recurved : outer lip 

 strengthened by the last-formed rib, ridged within by the 

 undersides of the spiral strice ; the intermechate furrows are 

 sometimes stained with purple : inner lip much thinner, and 

 never tuberculated : pillar ha\dng a shgliter fold : operculum 

 oval, more solid, but smaller. L. 1. B. 0-5. 



Habitat : Muddy estuaries of the Thames and Orwell 

 rivers, in 3-5 f. ; abundant. Brittany (Cailliaud) ; 

 Gulf of Lyons (Martin and J. G. J.); Bonifacio, with 

 IV. reticulata (Susini) ; Mogador, in mud (M^ Andrew) ; 

 Adriatic (Nardo). 



Among a number of specimens which I dredged in 

 the Roach River, one had two eyes on the right-hand 

 tentacle ; the eyes were smaller than usual, and close 

 together. 



This was noticed by Montagu as a variety of N. reti- 

 culata. I propose it as a distinct species with some 

 misgiving ; for, although I have not yet seen any inter- 

 mediate form, it has not been ascertained, that the two 

 live together, and the present form seems to be peculiar 

 to brackish water and mud. Both these last conditions, 

 however, prevail in Kiel Bay, where N. reticulata occurs 

 in a depauperated state. The difference between that 



