HALIOTIS 



Plate I. 



Genus Haliotis, Linnaeus. 



Testa ovaia, auriformis, planata, spird parva, brevissimd, la- 

 teralis peculiariter depressd; iutus margaritacea, pul- 

 clierrime prismatica, extus rugoso-costata aid corrugata, 

 raro lavi, latere sinistra phis miimsve angulnto, fora- 

 mimiin serie regulari ad angulimi perforata, nonnnUis 

 perviis; labro sinistra inflexo,planulato, dextro simplici; 

 aperturd amplissimd, propatuld. 

 Shell ovate, ear-shaped, flat, spli-e small, very short, lateral, 

 peculiarly depressed; pearly and very beautifully 

 prismatic within, roughly ribbed or wrinkled without, 

 rarely smooth, left side more or less angulated, per- 

 forated along the angle by a regular series of holes, 

 some of which are open ; left lip inflexed, flattened, 

 right lip simple ; aperture very large and wide open. 

 The genus Haliotis afi'ords an unusual abundance of 

 novelty from the cuxiunstance of it never having been 

 selected for the subject of an illustrated monograph ; the 

 species are, moreover, well defined, and may be easUy de- 

 termined by a careful examination of the variations of 

 sculpture and an-angement of colom's. 



The Haliatides are interesting in form as being the most 

 evolved and depressed of spiral shells, and they have been 

 arranged with the Chitons and Limpets as exhibiting the 

 nearest apparent affinity mth the non-spii-al Gastropods. 

 They present also a singularity of stiiicture in great mea- 

 sure analogous to the orifice in the shell of Fissurella or to 

 the fissm-e in Emargintda. On the left side of the shell, 

 in a dii'ect cui-ve parallel to the inflexed edge, is a row of 

 equidistant perforations, made by the animal in its progress 

 of gi-owth for conveying the water to the breathing organs ; 

 the mantle is slit in that direction to a certain extent, and 

 the water passes into the respii-atory cavity through a 

 tubular fUament protruding from each hole. The number 

 of paUial filaments being alike in the same individual 

 throughout its several stages of growth, the shell mostly 

 presents the same number of holes at all ages, filling up 

 the hindmost orifice as a new one becomes formed at the 

 margin. The SiUquaria presents a similar modification of 

 structure, and it has been also considered that the slit in 

 Pleurata7na is in some measure analogous. 



The internal surface of the ' Ear Shells ' is lined with a 

 bright pearly nacre, which in most species is of remark- 



able in-idescent brilliancy, glowing with all the colours of 

 the rainbow ; the attention must, however, be directed to 

 the outer coating of the shell, for the discrimination of 

 species, and it is with this view that the figiues in the 

 foregoing monograph are devoted mainly to external sculp- 

 tm-e. There is certainly a striking variation of character 

 in the nacre of diS'erent species, but the pattern of the 

 inner surface is merely an indentation of the outer. The 

 number of perforations vaiies in diflerent species, but may 

 be said to correspond in different individuals of the same 

 species ; where an exception occurs, it is that there is 

 sometimes one, or at most two, less in the adult than in 

 the young state; that is, when the animal arrives at ma- 

 tm-ity it continues to stop up one or two of the perforations 

 in advance of any new one. 



It is a cm-ious circumstance in the geographical distri- 

 bution of the Haliatides that few, if any, are to be fomid 

 where Chitons abound ; as if they exchanged places to a 

 certain extent ia the two hemispheres There are a few spe- 

 cies from California, but along the western coast of South 

 America, where Chitons are most abundant, not any are 

 found, and only one small species, the H. pulcherrima, at 

 any of the Islands of the Pacific. They inhabit the coasts 

 of China, Japan, Ceylon, Mozambique, Cape of Good Hope, 

 Borneo, and the Plulippine Islands ; but the greater num- 

 ber of species, and the most remarkable, are from New 

 Zealand, and the continent of New Holland, displaying all 

 the peculiai-ity of design wliich invariably characterizes 

 the fauna of those isolated regions. With the well-known 

 Haliotis tuberculata of the Channel islands, all are famUiar. 

 It is, however, a cii-cumstance worth noting, that although 

 such near neighbom's, and comparatively abundant, espe- 

 cially at the island of Jersey, it is rarely collected on the 

 coast of England. 



The Haliatides are found at low water, attached to the 

 under suiface of masses of stone, and they fix themselves 

 with great force to the rocks, by suction, on the least alarm. 



Although the genus Haliotis was descrilied by Lamarck 

 as being " assez nombreux en especes," only fifteen species 

 appear to have been known to that illustrious natm'aUst ; 

 six were added to that number by M. Deshayes, in his new 

 edition of the ' Aiiimaux sans vertebres,' and a few have 

 been described by Mr. Gray and others in scattered memoirs. 



April 1846. 



