1917.] NATURAL SCIENCES OF PHILADELPHIA. 283 



the figures of the plate as Ancilla cretacensis, but there is no reference 

 in his text to the species nor has mention of it been found elsewhere 

 in his writings. This figure does not show all the shell features but 

 it presents characteristics that seem sufficient to say that Conrad's 

 form is a species of the new genus Hyllus. 



The species, Hyllus callilateris, is the type of the genus and is 

 represented in the present collection by one specimen which is well 

 preserved except for the loss of the apex. The species is well charac- 

 terized by the broad flat body with a heavy callus deposit on the 

 body opposite the inner lip and further by the single columellar 

 plait. 



Hyllus coloratus n. sp. PI. XVII, figs. 3, 4. 



Description. — Shell of medium size and ovoid in outline; length 

 of aperture and anterior canal greater than the elevation of the spire; 

 whorls of conch probably four in number and increasing in size with 

 a fair degree of rapidity; sculpture absent, external surface smooth 

 and free from ornamentation except for incremental lines which show 

 through a brilliant glaze; suture indistinct, hidden by a glazed callus 

 which coats the entire surface of the shell; body evenly rounded 

 posteriorly and medially but gently constricted anteriorly into a 

 short broad pillar which is marked by a 'gently elevated anterior 

 fascicle formed by increments of the anterior siphonal notch; aperture 

 lenticular, produced anteriorly into a short canal; posterior siphonal 

 notch shallow and subangular, directly in front of posterior commis- 

 sure, notch indicated behind margin of aperture by incremental 

 lines; outer lip simple and smooth; inner lip excavated; columella 

 marked by two strong oblique folds; parietal wall thinly washed with 

 callus. 



Dimensions (imperfect individual). — Altitude 5.2 mm.; maximum 

 diameter 2.4 mm. 



There are two specimens of this species and both are incomplete. 

 One of these shows a dark yellow color banding which is fixed in the 

 glaze of the external surface and is no doubt a remnant of an original 

 color pattern. The species is well characterized by the two colu- 

 mellar folds which are conspicuous on the inner lip, the inornate 

 external surface and further by the subelliptical outline of the shell. 

 This species differs from Hyllus callilateris by being much smaller 

 and having two columellar plaits instead of one and further by not 

 having a heavy deposit of callus on the body opposite the inner lip. 



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