MEGASPIRID.E. 175 



Family MEGASPIRIDJE Pilsbry. 



Shell tapering-cylindric or turrite, long and slender, com- 

 posed of numerous whorls coiled about a hollow or at least 

 perforate axis, which may, however, be closed at the lower 

 end. Apex obtuse and rounded, rather large, but the summit 

 is sometimes truncate. Aperture small, irregularly ovate or 

 piriform, angular above, the outer margin of the peristome 

 thin, unexpanded or but slightly so. Cavity of the last or 

 preceding whorls obstructed by lamellae on the axis and often 

 on the parietal and outer walls also. Radula of the normal, 

 unspecialized Holopod type, the central teeth about as large 

 as the laterals ; lateral teeth with the ectocone developed, but 

 no entocone. 



A group of four or five genera, of apparently erratic dis- 

 tribution, as follows: 



Callionepion Pils., southern Brazil. 



Megaspira Lea, central-southern Brazil. 



Eomegaspira Pils., Paris and London Basins; Eocene. 



Perrieria Canefri, western New Guinea. 



Ccelocion Pils., eastern coast of Queensland. 



The soft anatomy is known only by a note by Fischer on 

 the teeth of Ccelocion, and by my own work on Callionepion, 

 Megaspira and Ccelocion. With the exception of Callionepion 

 (not certainly known to belong to the family), the data at 

 hand are confined to the jaw and radula. These organs are 

 of unspecialized type, like ordinary Helicidce, Eucalodiince 

 and Clausiliidce ; but the extraordinary characters of the 

 shell mark the Megaspirida as a group apart from these, and 

 from the Pupidce. Unlike most Urocoptidce, there is usually 

 no cord or keel defining the base of the shell, and the colu- 

 mellar lamella generally runs to the lip, and is visible from 

 in front. 



So far as I can see, in the present state of our knowledge, 

 the Megaspiridce seem to have been differentiated from their 

 allies, the Clausiliidce, in the Northern Hemisphere of the 

 Old World, during Mesozoic time. Eomegaspira represents 

 a branch which attained high specialization at the dawn of 



