228 Mr C. Collier on Univalves. 



In the genus Cypraa and in Bulla Ovum, the foot is like that 

 of the Coni ; in Bulla F'lcus and Buccmum DoUum, more circu- 

 lar ; in Bulla ampulla, the genus Voluta, and in Buccmum 

 Harpa and its varieties, it is extended anteriorly and posteriorly 

 beyond the shell ; in Haliotis and Patella flat, and of the di- 

 mensions of the disk ; in Serpula aquaria, a thick white mass, 

 against the summit of the shell. 



The colour of this part also varies ; blackish red in the Mu- 

 rices generally, green in Strombus, and some species of Trochus, 

 black in Bulla Ovum, deep red with faint designs, like those of 

 the shell, in Conus Tulipa, Marmoreus, and its varieties ; spot- 

 ted in Buccinum Harpa, bright yellow in B. Cassis, mottled in 

 Oliva, and deep brown from spots in some species of Voluta. 



The tentacula *, on which the eyes are borne, cannot be 

 designated by any general term employed for those processes 

 or the palpi in entomology. The most common form is taper- 

 ing, from a quarter to half an inch in length, with the eye in 

 the middle, and disproportionately thicker on the lower portion. 

 In the Strombi the eyes are on the summits of tentacula from 

 one to two inches long, of the same thickness, and which branch 

 off from the smaller foot, like the process containing the mouth. 

 They are short, thick, and bear the eyes on the outer side, 

 near the summit, in the Murices generally ; double, placed 

 above the mouth, with eyes at the base of the exterior, in Tro- 

 chus niloticus, and Turbo delphinus ; short and slender, with 

 eyes close to the apices, and placed at the sides, or extremities 

 of the covering of the tube, in Conus, some species of Buccinum, 

 in Bulla Ficus and Serpula lumbricalis ; in S. aquaria I could 

 not detect them. 



The nwuth is fleshy, or tubular and fleshy, or tubular only. 

 In the first case, it is composed of strong red muscular fibres, 

 uniting cartilaginous mandibles, in form not unlike narrow 

 blades of scissars. The next kind is a fleshy mouth within the 

 summit of the tube. The last is the tube opening directly into 

 the oesophagus, without triturating power, or tongue. 



" These processes in Volula are like those of Cyprcea, but, in some species, 

 as V. oliva, and a brown specimen, I could not discern eyes ; these organs nre 

 situated at the base of the lower tentacula, in Bul/a ampulla, as in Aplysiu. 



