. The Conchologists' exchange. Mollusks. 4 THE NAUTILUS. is an affinity between these so-called varieties and the species men- tioned, I have failed to discover it, though in possession, perhaps, of every form of the shells in question known to science. Certain writers also claim that the difference between and 0. textilina Lam. is merely varietal. Possibly this may be true; still, the facts do not appear to favor any such conclusion. On the contrary, the characters exhibited by large numbers of each clearly show them to be specifically distinct. It is just possible that intervening
. The Conchologists' exchange. Mollusks. 4 THE NAUTILUS. is an affinity between these so-called varieties and the species men- tioned, I have failed to discover it, though in possession, perhaps, of every form of the shells in question known to science. Certain writers also claim that the difference between and 0. textilina Lam. is merely varietal. Possibly this may be true; still, the facts do not appear to favor any such conclusion. On the contrary, the characters exhibited by large numbers of each clearly show them to be specifically distinct. It is just possible that intervening forms linking the two together are known, such for instance, as those uniting the typical 0. irisans with its admitted varieties 0. zelanica Lam., 0. tremulina, Lam., and 0. erythrostoma Lam. (Fig. 2), but if so they are certainly ab- sent from the several large collections of Olives belonging to mem- bers of the American Association of Conchologists and the Phila- delphia Academy of Natural Sciences. These are but a few samples of the difficulties at present barring the way to a thorough com- prehension of the specific relationship of the various members of the genus. The presence of such obstacles, however, should be to the earnest student more of a pleasure than an annoyance, since any effort for their removal will surely give him ample opportunity to exercise both his judgment and powers of observation. Despite the individual vagaries referred to, the genus is a thoroughly at- tractive one, many of the species, indeed, being unsurpassed Fig. 4 0. cryptospira Ford. Fig. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Averell, William D. Philadelphia, Wm. D. Averell
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectmollusks, bookyear188
