i2 Bulletin 29 176 



Actceon punctostriatus Dall (in part), Bull. Mus. Comp. Zool. Harv. 

 Coll., vol. 18, p. 40, 1889: Trans. Wagner Inst. Sci., vol. 3, pt. 1, 

 p. 14, 1890. Not A. punctostriatus C. B. Adams 1840. 



Shell ovate, with four and a half gently convex whorls, su- 

 ture well defined; outer lip thin, produced anteriorly; inner lip 

 with a slight callus; columella straight, bearing a single very 

 strong plication; last whorl ornamented with a series of fine 

 spirals, appearing under a lens as delicately puncticulate or finely 

 serrate lines which extend usually over half, but sometimes over 

 all the volution and are occasionally obsolete; examined under 

 the compound microscope the sculpture is seen to consist of nar- 

 row grooves, with cross bars, alternating with wider smooth 

 bands, the barred grooves producing the punctate effect when 

 less highly magnified. Length of large specimens 4.5, greatest 

 width 2.25 mm. 



Our species is evidently* that which Gabb also collected and 

 identified with d'Orbigny's recent Cuban shell A. punctata (La 

 Sagra, Hist. Pol. y Nat. Isla de Cuba, Atlas 8, pi. 17, figs. 10- 

 12). Since that name had been preoccupied by Lea, Gabb re- 

 named Orbigny's shell A. cubensis (Trans. Amer. Phil. Soc, vol. 

 15, p. 245, 1873). But the Dominican species is not identical 

 with the recent Cuban shell, which is only about half the size of 

 the Dominican fosssil, — measuring about 2.25 to 2.50 mm. and 

 having five whorls, while the fossil shells of that size are imma- 

 ture, with only three volutions. Moreover the plication of 

 the fossil is much stronger and the magnified sculpture of d'Or- 

 bigny's shell as figured is quite unlike that of our shell. 



Gabb's name A. cubensis should stand only for the recent 

 form called by d'Orbigny A, punctatus. 



*Gabb's specimens of this Actceon and all of his Dominican types have 

 been for two-score years in the possession of the Philadelphia Academy. 

 For years they have been undergoing a gradual revision. Until such time 

 as this is completed they are not available for comparative study. Fortu- 

 nately we have generally had access to Gabb's metatypes. 



