CCECUM. Panama, Shells. 163 



summits ; in the lower part with about 12 very stout prominent 

 not closely approximate rings with flat summits ; with 2 or 3 

 ribs on the middle with intermediate characters : apex pro- 

 minent. 



Length .09 inch ; breadth of the upper part .018 inch ; 

 breadth of the lower part .03 inch. 



This extraordinary shell appears like a monstrosity. It 

 cannot however be a deformed C. firmatum, since it is the last 

 half of the shell which resembles that species. If it were the 

 last half which is contracted, it would look more like the effect 

 of an accident. But accidents to mollusks do not, so far as we 

 have seen, cause a greater development of the shell. 



7 specimens, agreeing in all the above described characters, 

 establish the species. 



Station. Unknown. 

 Habitat. Panama ; C. B. A. ! 



217. Ccecum parvum. Nov. sp. 



Shell well arcuated, slender, of nearly uniform diameter : 

 white : with about 15 acute-edged moderately prominent distant 

 rings : apex lateral, prominent. 



Length .065 inch ; breadth .019 inch. 



Station. Unknown. 



Habitat. Panama ; C. B. A. ! 

 1 specimen was obtained. 



218. Ccecum pygiiueum. Nov. sp. 



Shell well arcuated, slender, of nearly uniform diameter: 

 white : with about 23 narrow but very prominent rings with 

 flattened summits : apex lateral, prominent. 



Length .06 inch : breadth .018 inch. 



Station. Unknown. 



