. The Echo. Mollusks. Muricacean Supraspecific Taxonomy Based on the Shell and the Radula George E. Radwin and Anthony D'Attilio San Diego Museum of Natural History Balboa Park, San Diego, California 92112 The present research has centered on the taxonomic use of the shell and radula in the gastropod family Muricidae. As a result, we feel that an approach to the present subject must encompass all forms with a similarity in morphology of the radu- lar dentition. To do this a survey of the entire superfamily Muricacea is necessary. Superfamily Muricacea. This is a generally homogeneous group tha
. The Echo. Mollusks. Muricacean Supraspecific Taxonomy Based on the Shell and the Radula George E. Radwin and Anthony D'Attilio San Diego Museum of Natural History Balboa Park, San Diego, California 92112 The present research has centered on the taxonomic use of the shell and radula in the gastropod family Muricidae. As a result, we feel that an approach to the present subject must encompass all forms with a similarity in morphology of the radu- lar dentition. To do this a survey of the entire superfamily Muricacea is necessary. Superfamily Muricacea. This is a generally homogeneous group that includes forms with conical or biconical shells bearing more or less strongly spinose or nodose sculpture. The radula is rachiglossate, consisting of three longi- tudinal rows of teeth—a three- five- or seven-cusped rachidian tooth and two simple, sickle-shaped laterals (Figure 1). The combination of this relatively simple, pectinate form of the rachidian, the simplicity of the sickle-shaped laterals, and the strongly sculptured shell is unique in the Figure 1. Generalized muricid radular dentition - 2/3 of a transverse tooth-row. Family Columbariidae. The members of this small, homogeneous group, numbering perhaps 15 to 20 species of worldwide distribution are readily distinguished from members of other muricacean families. The shell is relatively small and proportionally very elongate. Much of this length consists of an exaggerated, narrowly open, siphonal canal (Figure 2). The protoconch, according to Clench (19^^), consists of two bulbous, smooth whorls; the post- nuclear whorls are generally strongly carinated, with or without spinose projections. In most species a prominent spiral groove on the lower portion of the body whorl terminates in a moderately 55. 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
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