248 PROCEEDINGS OF THE NATIONAL, MUSEUM Vol.89 



ture specimens the umbilicus is broadly open and the umbilical wall 

 is marked by 4 spiral cords, which are strongly scalloped at their 

 junction with the axial ribs. 



The type, U.S.N.M. No. 493416, was collected by Dr. Victor Rodri- 

 guez at Finca Santa Maria (de Rivcron), Marti, Loma de Sibanicii, 

 Camagiicy Province. It has 4.2 whorls remaining and measures: 

 Length, 10.5 mm. ; greater diameter, 5.7 mm. ; lesser diameter, 4.8 mm. 



Genus TUDORA Gray 



1850. Tudora Gray, Nomenclature of molluscous animals and shells in the col- 

 lection of the British Museum, pt. I, Cyclophoridae, p. 48. 



Shell ranging from helicoid to elongate-conic in form, marked by 

 axial ribs only, or with axial ribs and spiral sculpture. The latter 

 may be confined to the umbilicus or it may be present on spire and 

 base. The axial sculpture varies from strong to almost obsolete, or 

 it may consist of slender, sublamellar riblets. The spiral sculpture 

 is equally variable as to strength in the different species. Breathing 

 devices may be present or absent in this genus. The operculum has 

 a basal chondroid plate composed of a number of whorls, the inner 

 edge of which develops a strong calcified lamella, which is reflected 

 outward until it parallels the basal chondroid plate, to which it is 

 connected by calcareous bars. The lamella extends to the outer edge 

 of the whorls of the operculum and thus forms a continuous surface 

 on the outside. The lamella is usually marked by fine, retractively 

 slanting striations or riblets. 



Type : Cyclostoma megacheilos Potiez and Michaud. 



KEY TO THE CUBAN SUBGENERA OF THE GENUS TUDORA 



Breathing device present. 



Shell with breathing siphon Eutudorops 



Shell with breathing puncture Eutudorex 



Breathing device absent. 



Early postnuclear whorls solute Bamsdenia 



Early postnuclear whorls not solute. 



Shell of helicoid shape Qtindlachtudora 



Shell not of helicoid shape. 



Peristome simple Wrightudora 



Peristome double. 



Axial ribs vertebrated Aguayotudora 



Axial ribs not vertebrated Tudorina 



Subgenus Eutudorops Henderson and Bartsch 



1920. Eutudorops Henderson and Bartsch, Proc. U. S. Nat. Mus., vol. 58, pp. 

 78-79. 



The first half nuclear whorl is microscopically granulose ; the rest of 

 the nuclear turns are marked by distantly spaced axial ribs. Shell 

 ranging from ovate-conic to elongate-conic, the axial sculpture of the 



