CALYPTRiEA. 



Genus CALTPTRiEA, Lamarck. 

 Testa ffloboso-coniea, tenuis, irregularis, vertice flerumque 

 rostrata, pellucido-alba, radiaiim dense mimUissime 

 striata, appendice interna obliqud, semi-infmidibuU- 

 formi; interdum valvam basalemformans. 

 Shell globosely conical, thin, irregular, generally beaked 

 at the top, transparent-white, radiately densely very 

 minutely striated, with an internal, oblique, semi- 

 funnel-shaped appendage; sometimes forming a basal 

 plate. 

 When M. Deshayes, in his edition of the ' Animaux sans 

 Vertebres ' of Lamarck, came to examine the Cup-and- 

 Saucer and Slipper Limpets, comprised respectively in the 

 genera Calyptraa and Crepidula, he found them to be so 

 nearly allied to each other as to desire that they should 

 be united into a single genus, after the manner of Helix 

 and CarocoUa. " There exists a certain number of par- 

 ticular forms," said M. Deshayes, " to serve for grouping 

 them in sections, but the internal appendage, which in 

 some Calyptraa is funnel-shaped, passes insensibly into 

 the trochiform appendage of others, and into the septum 

 of Crepidula ; and the two genera must therefore be 

 united." "This conclusion," continues the learned editor, 

 " which we have in some degree foreseen, has been rigor- 

 ously drawn and acted on by incontestable evidence, in 

 a paper recently published by Mr. Broderip in the first 

 volume of the Transactions of the Zoological Society." 



Since the foregoing was written, the discovery of the ani- 

 mal of Calyptraa equcstris has afforded evidence, not only 

 that the Crepidula are distinct, but that the sections of 

 Calyptraa indicated by M. Deshayes should be regarded 

 as genera of the same rank. I propose, then, to retain 

 Crepidula in its Laraarckian form, and for the eup-appen- 

 daged, and the trochoid, Calyptr/pa to adopt the genera 

 respectively instituted for them by Schumacher, Crucibu- 

 lum and Troc/iUa. It will be seen presently that the three 

 very characteristic groups hitherto included under the head 

 of Calyptraa cannot be regarded as sub-genera of a rank 

 inferior in the scale to Crepidula. The Calyptraa proper, 

 represented by the Linnasan Patdla equeslris, are all cha- 

 racterized by a shell of peculiarly fine, semitransparent 

 thread-like tissue, and it may be fairly inferred that the 

 animal which has been shown to be distinct in one species, 

 corresponds with the shell in its distinctness in all. 



When Mr. Cuming visited the island of Zebu, one of 



the Philippine group, about twenty years since, he ob- 

 served on some coral reefs a number of dead shells of Ca- 

 lyptraa equeslris. Supposing that living specimens could 

 not be far off, he was induced after considerable search to 

 turn over a mass of coral that lay sunk about two feet in 

 the sand, just below low-water mark. To his surprise, he 

 found the living Calyptraa equeslris attached by the foot 

 to a separate calcareous plate. Upon further search he 

 discovered specimens of other species similarly attached, 

 and some also at the island of Bohol ; and having captured 

 the animal, he submitted it to Professor Owen for dissec- 

 tion. The phenomenon was observed about the same time 

 at Mahe, one of the Seychelle Islands, by M. Dufo, a dis- 

 tinguished French conchologist, but no dissection appears 

 to have been made by him of the animal. Professor Owen 

 found the animal to differ from other known forms of Calyp- 

 traida " in the smaller development of its locomotive and 

 respiratory organs, and in the greater development of the 

 organs for the prehension and assimilation of food." " The 

 foot," continues the Professor, " may well offer diminished 

 proportions when the animal has chosen a site for the de- 

 position of its ventral plate, and has taken up a fixed 

 abode. Muscular action being thenceforward much re- 

 stricted, the necessity for extensive respiration is in the 

 same degree abolished." 



The C. tectum- Sinense was the only other species of this 

 group known to Lamarck, but attention having been drawn 

 to them, upwards of thirty have been collected, chiefly 

 from the Philippines, Moluccas, and Galapagos Islands, 

 but some from Honduras, the West Indies, Ceylon, and 

 Australia. 



Species 1. (Pig. 1 a, b, c, Mus. Cuming.) 

 Calyptk.«a euuestris. Calyp. testa suborbiculari, soli- 

 dluscnld, rude convexd, vertice irduute rostrata, alba, 

 prope marginem. fulvescente, radiatim tenuiliratd, liris 

 acutis, compressis, nndulatis, subluberculatis, intersti- 

 tiis radiatim minute striatis ; appendice interna sub- 

 ampld; valvd basali ampld, concavd, patellaformi, 

 margine irregulariter obscure corrugatd. 

 The knightly Calyptr.£a. Shell nearly orbicular, 

 rather solid, rudely convex, minutely beaked at the top, 

 white, fulvous near the margin, radiately finely ridged, 

 ridges sharp, compressed, a little waved, somewhat 

 tubercled, interstices radiately minutely striated ; in- 



Deeember, 1858. 



