156 SERPULA. CREEPER. 



Shell glossy white, opake, rather flat, oblong-oval, with 

 three compartments j on one edge is a single longitudinal 

 suture apparently dividing it into two parts ; on the other 

 side a faint depression investing the middle compartment 

 which is more raised, and separating it from the outer- 

 ones : aperture produced into a very short neck, oval and 

 ^dged with yellow : length not half a line. 



In fine sand : very rare. v. m. 



19. Serpula bicornia. Tivo-horned Creeper, 

 Walker, f. 2, 



Shell glossy white, opake, flattish, somewhat oval, 

 smooth on the upper side, striate longitudinally from the 

 aperture on the other ; aperture contracted, small, orli- i; - 

 lar : length a line. 



Variety. Perforated in the centre. 



Walker, f. 3. 



Jn fine sand ; very rare. v. m, 



20. Serpula incurvata. Curved Creeper. 

 Walker, i. 11. 



Shell white, semitransparent, smooth, cylindrical, 

 straight, but curved at the smaller end into three close vo- 

 lutions or compartments : length hardly a line. It resem- 

 bles the Nautilus semilituus, but is perfectly smooth and 

 cylindrical, and has neither syphon in the aperture, nor in- 

 ternal cellvS nor joints. 



Variety. With a single volution at the end, and pervious. 



Walker, f. 12. 



Jn fine sand : very rare, v. m, 



The three first species of this subdivision are evidently 

 distinct from each other in the form of the aperture, which 

 never interchangeably varies, although Mr, Dillwyn has 

 United them -, the fourth he has omitted altogether, 



D, Detached, and bottle-shaped, 21 to 29. 



21. Serpula lactea. Egg Creeper, 



Walker, f. 5, 



Shell thin, transparent, egg-shaped but a little flattened, 

 With generally four milky lines.- separating the compart- 



ments, 



