Science. 1961 Aug 11;134(3476):393-4. doi: 10.1126/science.134.3476.393.
Littorina littorea, an abundant northeast North American gastropod, was thought to have been introduced from Europe about 1840. Shells of that species found in ancient Micmac Indian camp sites in Nova Scotia have been radiocarbon-dated as pre-Columbian. Failure of L. littorrea to extend its range southward before 1840 may have been due to oceanographic factors.
紫贻贝，一种分布广泛的东北北美腹足纲动物，据认为是在 1840 年左右从欧洲引入的。在新斯科舍省的古老 Micmac 印第安人营地遗址中发现的该物种的贝壳已经被放射性碳定年为哥伦布之前的时期。在 1840 年之前，L. littorrea 未能向南扩展其分布范围，这可能是由于海洋因素造成的。
