MEGASPIRA. 181 



radula figured the 3d lateral on one side is abnormal, perhaps 

 by concrescence of two rows of teeth. 



The soft anatomy is otherwise unknown. 



Type M. ruschenbergiana. Distribution, interior of Brazil, 

 prov. Minas Geraes. No fossil species are known. 



The data now available bearing upon the phylogeny of 

 Megaspira are quite insufficient for the formulation of a defi- 

 nite opinion. The radula is all that is known of the soft 

 anatomy, and this is of the generalized type common to many 

 families of Holopoda. I formerly thought that the group 

 was related to the Urocoptida, but further study of that 

 family causes me to renounce that opinion. Fischer and many 

 others have placed Megaspira in the heterogenous family 

 Pupida. The investigation of Eomegaspira, a genus char- 

 acteristic of the lowest Eocene of the Paris and London 

 Basins, gives a clue to the past history of Megaspira, which 

 probably descended from an ancestral stock which crossed 

 from Africa to tropical Brazil. 



Little is known of the habitats of the several species. Most 

 specimens in collections were procured in Rio de Janeiro, 

 where they were brought from the interior. The allusion to 

 Megaspira in Proc. Malac. Soc. Lond., i, p. 308, is an evident 

 error for Macrospira. 



Key to Species of Megaspira. 



I. Shell wifch 3 columellar lamellae, the lower one (subcolu- 

 mellar) penetrating several whorls on the lower side of 

 the median or columellar lamella; one of the lower radial 

 laminae continued in a spiral cord in the base of the last 

 whorl. Length of shell over 50 mm., whorls about 23. 



M. ruschenbergiana, no. 1. 



II. Shell with the supracolumellar and subcolumellar lamellae 

 shorter and inconspicuous within ; no spiral basal cord in 

 any whorl. Smaller shells. 



1. Baso-axial radial laminae or barriers high, most of 

 them with a small hook at the axial end; external 

 sculpture rather coarse. 



a. Columella 2-folded, the lower fold bifid; shell 



