Occasional Papers of the Museum of Zoology 25 



ical spiral is also variable, but, in all of my specimens, at least 

 two can be detected. In addition, traces of spirals are present 

 on the sides of the earlier whorls. The aperture of adult spec- 

 imens is always solute, angulate above, and with the peristome 

 free and slightly expanded. This expansion is most noticeable 

 on the lower portion of the palatal wall, but is least extensive 

 along the base. 



The females are considerably larger than the males : repre- 

 sentative examples of each measure: 



Altitude Maj.Diam. Altitude Aperture Diam. Aperture 



Female 17-3 53 (9-2) 38 (6.5) 85 (5.5) 



Males 14.5 54 (7-8) 36 (5.2) 87 (4.5) 



12.4 55 (6.8) 34 (4-2) 91 (3-8) 



Pfeilter also described Cyclostoma tamsiana from Puerto 

 Cabello. According to his description, the calcareous plate of 

 the operculum is the only important character that separates it 

 from C. plicatuliim. As detailed above, this character is a 

 doubtful one. However, he emphasizes the central position 

 of the nucleus of the operculum of C. tamsiana, and it is just 

 possible that he had immature specimens (peristome simplex) 

 of T. zdlliamsoni sccana (see below) before him. FfeilTer's 

 own figure (Conch. Cab., xxxvii-19, 20) might represent the 

 latter, but Reeve's (1863, Conch. Icon.) is certainly T. plica- 

 tula, and Pfeiflfer (1865) recognized it as authentic. All of 

 the Puerto Cabello specimens in the A. N. S. P. are T. plica- 

 tula, although some of the lots, with better preserved opercula. 

 have been labeled tanisia)m: In this connection, attention 

 should be called to the habit of earlier collectors, who very 

 commonly named, as the locality of their specimens, some 

 large, well-known town in the general region. Labels such as 

 Puerto Cabello and Caracas may mean but little more than 

 labels like Venezuela or New Granada. 



