A conchological manual . s in Lithodomus (fig. 161 in theplates). It is cordiform when the shape presents a resem-blance to an imaginary heart, as in Cardium cardissa (fig. 122in the plates), and in the Isocardia (fig. 126 in the plates). Itis linguiform when it resembles a tongue in shape, as inVulsella (fig. 185 in the plates); rostrated when it protrudes INTRODUCTION, 39 at either extremity, and terminates in a kind of point, as inSanguinolaria Diphos (fig 99 in the plates); truncated whenit ends in a square or angle, as if cut off; an example ofwhich may be seen in Solen (fig. 60 in the pl
A conchological manual . s in Lithodomus (fig. 161 in theplates). It is cordiform when the shape presents a resem-blance to an imaginary heart, as in Cardium cardissa (fig. 122in the plates), and in the Isocardia (fig. 126 in the plates). Itis linguiform when it resembles a tongue in shape, as inVulsella (fig. 185 in the plates); rostrated when it protrudes INTRODUCTION, 39 at either extremity, and terminates in a kind of point, as inSanguinolaria Diphos (fig 99 in the plates); truncated whenit ends in a square or angle, as if cut off; an example ofwhich may be seen in Solen (fig. 60 in the plates). Other Bivalves are distinguished as being auriculated,having processes flattened and expanded on either side of theumbones, as in Pecten (cut, fig. 82). When there is one ofthese on each side of the umbones, it is bi-auriculated; v/henonly on one side, it is uni-auriculated. When the expansionis very broad, as in Unio alatus (fig. 142 in the plates), andin the Hammer Oyster (cut. fig, 83), the term alated is Fig. 82, aurieulated; 83, auriculated, aluted. With regard to these alated species of Uniones, it is neces-sary to observe that they are also advate,* as it is termed ;the two valves being joined to each other by the dorsal edgeof the expanded parts, and united so completely in substancewith each other, that they cannot be separated without beingbroken. Many other terms are used to express difference inBivalves, but being generally applicable to Univalves andMultivalves, as well as to them, they will be found explainedat large in the alphabetical part of the work. MULTIVALVE SHELLS. These are of three different kinds; first, the dorsal asthey are termed by Linnaeus, because they form a ridge in theback of the animal. They are composed of eight pieces, or 40 INTRODUCTION. separate valves, placed in a longitudinal series, being joined toeach other by inserted lamina, and named Articulata by DeBlainville, on that account. The genus Chiton is the onlyexample of th
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Keywords: ., bookcentury1800, bookdecade1840, bookidconchol, booksubjectshells
