6o BUI.LBTIN 39 23a 



Genus ANCISTROSYRINX Dall 



Ancistrosyrinx elegans Dall, variety Plate 4, figure 17 



Ancistrosyrinx elegans Dall, 1881, Bull. Museum Comp. Zool., vol. 

 9. p. 54- 



Ancistrosyriiix' elegans Dall, 1889, Bull. Museum Conip. Zool., voL 

 18, pt. 2, p. 78, pi. 38, fig. 3. 



The discovery of this elegant, recent species in the Gatiin 

 beds of Costa Rica is of more than usual interest, the record 

 being based on a single, small but otherwise quite t5^pical speci- 

 men from Hill la of the Banana River. Com.parison with Ball's 

 figure in the Blake Report, shows no important difference, ex- 

 cept that the sculpture of the fossil shell is somewhat finer. 



A. clegous, is recorded by Dall from the Florida Reefs and 

 from 805 fathoms of water oif Havana, Cuba. 



The dimensions of our shell is as follows: Length 15, diam- 

 eter 5.75, last whorl 11 mm. 



Gatun Stage: Hill la, Banana River. 

 Ancistrosyrinx Dalli, n. sp. Plate 4, figure 16 



Shell larger than the preceding and very nearly smooth; nu- 

 cleus very small and smooth; post-nuclear whorls seven or more 

 with a large and prominent, dentate or spinous keel; between 

 the keel and the suture, there is a wide, nearly flat area, which 

 carries a strong, smooth, median, spiral cord, behind which lies 

 the small concave anal fasciole; the rest of the shell is smooth 

 and without spirals ;on the last whorl, the peripheral keel carries 

 about 18 short, broad, spiny teeth; the canal is long, slender and 

 straight; outer lip thin and fragile. 



Length 14, diameter 7, last whorl 9,5 mm. 

 20 10, 15 mm. 



Two specimens are represented in our collection, and the 

 smaller but more perfect specimen is selected as the Holotype. 

 It differs from the described species of A?ieisfrosyrinx by its 



