MELLITA PACIFICA. 77 



and have a conspicuous hook or tooth, or usually two or three of them at the tip 

 (PI. 125, fig. 21) but seen from within they are broad and the tip has several 

 dentate projections; there is also a calcareous meshwork in the blade (PI. 125, 

 fig. 19). The biphyllous are less distinctive; they have somewhat hood-shaped 

 valves (PI. 125, fig. 20) about .07 mm. long. 



This is the common "key-hole urchin" of the Florida coasts. The tests 

 are found as far north as Nantucket and even in Vineyard Sound but the exact 

 northern limit of the living animal is not known. It is common at Beaufort, 

 N. C. and southward extends to Brazil. 



Mellita longifissa. 



Michelin, 1858. Rev. et Mag. Zool., 10, p. 360. 



Pedicellariae are very scarce but resemble those of sexiesperforatus. The 

 geographical range of longifissa is from the Gulf of California to Panama. 



Mellita sexiesperforata. 



Echinodiscus sexiesperforatus Leske, 1778. Add. ad Klein, p. 135. 



Mellita sexiesperforata Meissner, 1904. Bronn's Thier-reichs, 2, abt. 3, buch 4, p. 1384. 



Plate 125, figs. 22, 23. 



The pedicellariae (PI. 125, fig. 23) of this species are recognizably distinct 

 from those of quinquiesperforata, the most striking difference being that the 

 valves of quinquiesperforata will lie flat on their backs while those of sexies- 

 perforata are so compressed that they will not. The valves (PI. 125, fig. 22) 

 are very small, only .10-. 15 mm. long and the blade usually ends in a single 

 sharp tooth. 



This species occurs at the Bermudas and is known from Charleston, S. C. 

 Southward it extends at least to Uruguay. 



Mellita pacifica. 



Verrill, 18G7. Trans. Conn. Acad., 1, p. 313. 



Nothing is known of this species beyond the original description. I cannot 

 avoid the feeling that it is an Encope and not a Mellita and is possibly identical 

 with E. micropora. The type specimens were from Zorritos, Peru. 



