444 PROCEEDINGS OF THE NATION'AL MUSEUM vol.89 



States National Museum. Finally, it seems best to refer to this 

 variety three large specimens that Alexander Agassiz collected many 

 years ago at Captiva Key, Fla., near Sanibel Island. These speci- 

 mens range from 100 by 110 mm. to 129 by 129 mm. and are notably 

 thicker and solider than typical tenuis^ and the apex is evidently 

 central or anterior. Such specimens prove that tenuis is not a well- 

 defined species yet. But typical examples of this Mellita are so 

 conspicuously different from ordinary qidnquies'perfoTata that when 

 the Tarpon Springs and Charlotte Harbor specimens were first 

 examined it seemed quite clear that they represented a well-marked 

 species characteristic of the west coast of Florida. The large series 

 available of the common species shows, however, that there are nmner- 

 ous connecting links, and the conclusion was reluctantly reached that 

 tenuis must be rated as a variety merely. There are specimens at 

 hand from the Carolina coast that are so similar to those from 

 Sanibel Island that they cannot be distinguished by constant meas- 

 urable characters. On the other hand, there are the three large speci- 

 mens from Captiva Key, mentioned above, which are too much like 

 ordinary quinquiesperf Grata to justify specific separation. An inter- 

 esting point in the matter is that specimens from the coast of Texas 

 and western Louisiana are normal quinquiesperf orata. 



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