MUSEUM OF COMPARATIVE ZOOLOGY. 115 



Tornatina parviplica n. sp. 



Figure 8. 



This species resembles T. recta Orb. in a general way, especially when 

 young, and is distinguishable from it by its more rounded surface between the 

 sutures of the spire, and by the obsolete plait on the pillar; the adult is 

 a much thinner yet wider shell than T. recta, and reaches a length of 6.5 and 

 a width of 3.25 mm., with five whorls, beside the projecting sinistral nucleus. 

 The spire is moderately elevated, the top of the last whorl llattish, but without 

 canaliculation ; the surface is faintly marked with lines of growth, not polished, 

 and entirely without spiral sculpture. The umbilicus is not perforate, and the 

 plait is formed by the twisting of the thickened pillar, not superposed upon 

 the pillar. It is only known from the lagoons. 



Assiminea Auberiana Orbigny. 



A single normal specimen of this species turned up. It is known from the 

 Antilles generally, and from South Florida. 



Cerithium (Pyrazus) Rawsoni Krebs. 



Figure 13. 



This is another form strictly confined to the lagoons, and has the thin shell 

 and mottled purple and brown coloration shown by a number of the lagoon 

 shells. Its open sea analogue is C. mutabile C. B. Adams. The original speci- 

 mens of Rawsoni were of doubtful origin, but it is now well known to he from 

 the Bahama lagoons. 



Cerithium (Pyrazus) septemstriatum Say, 

 var. degeneratum Dall. 



Figure 11. 



These thin shelled, brightly colored, abnormally small specimens still retain 

 enough of their characters in some individuals to be referred to septemstriatum 

 as a variety, characterized by intensity of color and general depauperation in 

 other features. The axial sculj)ture is almost entirely lost, but the fine spiral 

 striation is as usual unaffected by these changes. The colors are chiefly bluish 

 white, purplish brown, and various shades of gray, which are prettily mingled 

 in a variety of patterns. The shells are usually about 12 mm. long, not one 

 fourth the size of the open-sea septemstriatum, yet their variability is so great 

 and the chain of intermediates so complete that T cannot regard the lagoon 

 form as having reached the point of specific distinctness. The species is widely 

 distributed in the Antilles and on the coa.st of the United States. 



