It will be difficult to determine the origin of this curious practice. We shall not be able to say that it came from the elaboration of handles, simply to please fancy, for the reason that vessels of this class are rarely known to have had simple handles; nor from the modification of simple ornaments, as such were but little used. It is still less probable that animal forms were first modeled independently, and afterwards changed in such a way as to serve as vessels. There are no examples of animal forms in clay independent of vessels. It would not be consistent with primitive methods of procedure to copy nature direct, at least until some mystic significance had become attached to the form employed. It is possible, however, that the origin of this practice is not to be found within the plastic art itself, but in the shapes of antecedent and co-existent vessels of other materials in which life forms had been employed; or in the use of natural objects themselves as utensils, the original forms not having been lost sight of and having in time suggested the employment of other natural forms. Examples of the latter class may be cited. Shells were primitive vessels. The hard cases of seeds and fruits were also much used. These were doubtless antecedent to vessels of clay. They were the natural models for the potter, the carver in wood or stone, and their employment as such served to lead up gradually to a more realistic and general use of natural shapes in works of art to which they were not essential features. The importance of the various animal forms was increased by their association with religious ideas. Nearly all the vessels of this class presented in the following illustrations come from the vicinity of Pecan Point, Arkansas. Clay vessels imitating both marine and fresh-water shells are occasionally obtained from the mounds and graves of the Mississippi Valley. The conch shell appears to have been a favorite model, especially in its modified form, Fig. 374, _a_ and _b_. The clam shell is also imitated in _c_ and _d_. The more conventional forms of these vessels are exceedingly interesting, as they point out the tendencies and possibilities of modification. An instructive example illustrated in _e_ has four groups of nodes, each, consisting of a large central node with four or five smaller ones, surrounding it, set about the rim, the conception being that of four shells joined in one vessel, with the noded apexes turned outward and the bases inward. A still more highly conventionalized form is shown in _f_. The cup is unsymmetrical in outline, and has a few imperfect nodes near one corner, but its resemblance to a shell would hardly be recognized by one unacquainted with more realistic renderings of like subjects. In _g_ we have an imitation of a shell cup placed within a plain cup. [Illustrations: FIG. 374.--Clay vessels imitating shells.]