FISSURELLA 



Genus Fissukella, Bruguicre. 

 Testa depresso-couica, ovata vel oblongo-ovata, dypeifonuis, 

 plerumque antice attenuala, radiat'mi striata vel costata, 

 stmimitate perforata, orificio ohlongo, vel sitborbiculai-i, 

 laferibtts nunc coardato, nunc excavato, sapissime 

 antice inclinato. 

 Shell depressly conical, ovate or oblong-ovate, shield- 

 shaped, generally attenuated anteriorly, radiately 

 striated or ribbed, perforated at the summit, orifice 

 oblong, or nearly orbicular, sometimes contracted, 

 sometimes excavated at the sides, most frequently 

 inclined anteriorly. 

 The Fissierella, or Key-hole Limpets, constitute an 

 attractive group, distinguished rather for their beauty and 

 variety of painting, than for any remarkable development 

 of sculpture. The orifice at the summit of the shell, which 

 constitutes the principal character of the genus, is mostly 

 inclined anteriorly, that is, in the direction of that portion 

 of the shell covering the head of the mollusc, and which 

 is generally more or less attenuated. The orifice varies 

 characteristically in form in different species, but not in 

 individuals of the same species. It is mostly oblong, 

 sometimes a little excavated at the sides, but more fre- 

 quently contracted in the middle, in such a manner 

 as to give a denticulated character to the margin. In 

 one species, F. aperta, the orifice is considerably larger 

 than in any other, and the animal, as figiu-ed by 

 M. D'Orbigny, is seven or eight times longer than the 

 shell ; in another, F. macrosc/iisina, the orifice is stretched, 

 so to speak, nearly to the anterior basal edge. The sculp- 

 ture consists of ribs or ridges radiating from the dorsal 

 orifice to the base, and an agreeable pattern is sometimes 

 produced by the development of concentric ridges, which 

 are squamate at the point of crossing. 



The largest and most brilliantly painted Fissurellts are 

 fi-ora the western coast of South America. During 

 Mr. Cuming's sojourn in that country, he collected several 

 species on exposed rocks, at low water, larger and finer than 

 any before known. At the Philippine Islands, on the 

 contrary, Mr. Cuming observed only a few species of small 

 size ; nor were any collected during the voyage of the 

 Samarang among the Islands of the Eastern Seas at all 

 approaching in size to those of Chili and Peru. 



Species 1 (Fig. a and b. Mus. Cuming.) 

 FissuEELLA Chemsitzii. Fiss. testd ovaid, antice at/e- 

 nuatd, depressiuscidd, lateribiis pecidiariter compressd, 

 extremltatibus levatis ; radiatim costata, costis rudibus, 

 incequalihus, obsolete nodosis, Mc illic tumidiusculis, 

 orificio ovali, ample ; olicaceo-viridi et purpureo-roseo 

 tincld et radiatd. 

 Chemnitz's Fissurella. Shell ovate, attenuated an- 

 teriorly, rather depressed, peculiarly compressed at 

 the sides, lifted at the extremities ; radiately ribbed, 

 ribs rugged, unequal, obsoletely nodose, rather 

 swollen here and there, orifice oval, large ; stained 

 and rayed with olive green and purple-rose. 

 SowERBY, Pro. Zool. Soo., 1831., p. 12(5. Conch. Illus. 



f. 55. 

 Ilab. Benguela, W. Africa ; Dr. Tarns. 



There can be no impropriety in dedicating this species 

 to the author of the latter volumes of the ' Conchylien 

 Cabinet;' but it is not identical with the figure of his 

 predecessor (Martini, vol. i. pi. 11. f. 100), to which 

 Mr. Sowerby refers it. The ribs are fewer in number and 

 more unequal, wliilst the orifice is totally different. To 

 the specimen formerly in the Tankerville collection, is 

 here added a figiu-e of a smaller one in finer condition 

 collected at Benguela by Dr. Tarns. 



For Species 3 see Plate IV. 



Species 3. (Mus. Cuming.) 



Fissurella neglecta. Fiss. testa ovatd, antice atte- 

 nuutd, medio postice levatd, radiatim costata, costis ru- 

 gosis, incequalibns, obsolete nodosis, summitatem versus 

 eximie cancellatis, tnargine basali bifide crenulato, ori- 

 Jicio oblongo-ovato, lateribns mdicoarctato ; cinerascente, 

 fasciis concentricis nigricantibtis radiisgue oUvaceis 

 subobscuris variegatd. 



The neglected Fissurella. Shell ovate, attenuated 

 anterioriy, raised posteriorly in the middle, radiately 

 ribbed, ribs rugged and unequal, obsoletely nodose, 

 delicately cancellated towards the summit, basal 

 margin creuidated in a bifid manner, orifice oblong- 

 ovate, slightly contracted at the sides ; pale ash colour, 

 somewhat obscurely variegated with blackish con- 

 centric bands and olive rays. 



August, 1819. 



