PLATE XI {continued). 



54. — N. comnntnis, West Indies. Odontofore smaller than former and teeth 

 finer. Median minute, refiexed, apical. Uncini, 1st large, trans- 

 verse, flattened as it approaches the 2ud, wiiich is sniiill and re- 

 flexed. 3rd subopaque, trapezoidal ; head large, having the 

 apjiearance of a double-headed hammer placed on the flat, the 

 extreme portion being much produced and hooked. Uncini nume- 

 rous, small, hooked, diminishing outwards. 



55. — N. Mauri, West Indies. Median subquadrate, reflexed, apical, nar- 

 row towards base. Uncini, 1st broad, reflexed ; 2nd small, 

 reflexed, and narrow ; 3rd large, subopaque, trapezoidal, having a 

 broad, hood-shaped head. Uncini numerous, hooked, diminishing 

 outwards; an elegant band, well suited for polarized light. Tliis 

 group show a close affinity to Helicina, the formula properly 

 a 3 — 1 — 3 oo. 



56. — Haliotis iuherculata, Guernsey. Median subquadrate, base produced 

 outwards, reflexed. Uncini, 1st resembles a shoulder-girdle, articu- 

 lating with a subopaque tooth of remarkable strength, hooked ; 

 this is followed by others similar but smaller. Uncini about sixty, 

 first four very large, gradually diminishing outwards. The specimen 

 is mounted dry, and well displays itself under polarized light. 

 There are several other specimens of the same in cabinet ; the bold 

 shark-tooth-like appearance of the first of the uncini is very 

 striking. The odontofore strongly resembles that of Trochus. 



{To be continued^ 



