THE SLIT SHELLS - FAMILY PLEUROTOMARIIDAE Shell top-shaped, pearly within, with a broad anal sinus in the outer whorl which closes gradually, forming the "sinus band." A family of many fossil forms allied to Haliotidx.
Genus PLEUROTOMARIA, Defr.
Characters of the family. Eleven hundred fossil species of this genus are known. The recent discovery of living forms corrects the old opinion that the genus is totally extinct. Twenty good specimens have been collected in the past fifty years. They are large, and so distinct in kind as to be in great demand among collectors. The single specimen of P. Quoyana, F. and B., was purchased by an amateur in 1873 for 25 guineas. A fine large P. Adansoniana, Cr. and Fisch., is priced at L oo sterling.
Both of these species have been found in the region of the West Indies. The American Museum of Natural History has a three-inch specimen of P. Beyrichi, Hilgendorf, which was dredged in deep water off the coast of Japan. It is decorated with yellow and red in fine streaks on its top-shaped spire, and the sinus band ends in a deep slit at the upper (sutural) edge of the lip. The largest Adansoniana, taken alive from water one hundred fathoms deep off Guadaloupe, measured more than five inches across.
The Little Slit Shells (genus Scissurella) are very small, thin-shelled mollusks with the tell-tale slit in the shell's lip.
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