42 CLASS III. GASTEROPODA. ORDER III. CERVICOBRANCHIATA. 
cavity, analogous in some measure to the vertical hole in those of the 
Fissurelle. The holes are ranged in a straight line running parallel with 
the columellar lip ; and being required only in that part of the shell which 
covers the branchial cavity, those nearest the spire become filled up, 
whilst new ones are formed as the shell advances in growth. 
The Haliotides exhibit a very peculiar assemblage of characters, and 
authors have been much divided in their opinions as to the situation they 
should occupy in the natural system. Linnzeus considered them as afford- 
ing a transition from the non-spiral to the spiral univalves, placing them 
next to the Patelle ; Lamarck regarded them at one time as intimately 
allied to the Chitones, but subsequently to the Szgareti and Nerite ; whilst 
Cuvier and De Blainville have rather approached to the arrangement of 
Linneus in placing them near to the Capulacea. 
The genus Padollus of De Montford was proposed for those species 
whose shells exhibit a longitudinal groove. 
The shell of Haliotis may be described as being ovate or ear-shaped, 
more or less depressed, and perforated witha straight series of holes ; the 
inside is pearly and prismatic, the outside rough and often wrinkled ; the 
spire is very short and sublateral ; the aperture large, and the columella 
generally flat 
Examples. 
Pl. CL. Fig. 1. 
Hatioris excavata, Lamarck, Anim. sans vert., vol. vi. part 2. p. 215. 
PL. CL. Fig. 2. 
Hatroris astnrna, Linnzus, Syst. Nat., p. 1256. Martini, Conch., 
vol. i. pl. 16. f. 150. 
Haliotis asinium, Gmelin. 
Pl. CL. Fig. 3. 
Hattotis parva, Linneus, Syst. Nat., p. 3689. Martini, Conch., vol. i. 
pl. 14. f. 140. 
Haliotis canaliculata, Lamarck. 
Padollus ? De Montford, Gray. 
