N0.228S. NEW MOLLUSKS OF THE FAMILY TURRITIDAE—DALL. 17 



the ribs extending well over the base from the anterior margin of 

 the anal fasciole, where they form a marked shoulder; the incre- 

 mental lines are hardly noticeable except on the fasciole; spiral sculp- 

 ture of (on the spire three) strong cords, the posterior slightly 

 larger, which become swollen and nodulous where they intersect the 

 summit of the ribs; on the last whorl there are 7 of these cords 

 and 10 minor threads in front of the base and on the canal ; in the 

 interspaces between the major cords there are from one to three fine 

 threads which do not become nodulous ; anal fasciole narrow, concave, 

 somewhat removed from the suture, the sulcus shallow ; in the type- 

 specimen the outer lip is thin and sharp, the inner lip erased, but if 

 the specimen is immature the outer lip would probably be thickened 

 with a subsutural callus in the adult; pillar straight, attenuated in 

 front, white; canal distinct, not recurved. Height of shell, 16.5; 

 diameter, 8.5 mm. Cat. No. 211516, U.S.N.M. 



Range.— Station 2828, in 10 fathoms, oflf La Paz, Lower California. 

 U. S. Bureau of Fisheries. 



CARINODRILLIA, new section. 



For the species in which the spiral sculpture predominates and in 

 which there is a tendency for the peripheral cord to form a carina, 

 the name Carlnodrillia is proposed with Clathrodrillia halis Dall, as 

 the type. This forms a very natural group containing a large num- 

 ber of species mostly unicolor, whitish or brownish. 



CLATHRODRILLIA (CARINODRILLIA) HALIS, new species. 



Plate 5, fig. 4. 



Shell yellowish white, elongated, acute, with two polished, more 

 brownish nuclear whorls and nine subsequent whorls; suture ap- 

 pressed with an angular thread in front of it, separated by an ex- 

 cavated wide fasciole, microscopically spirally striated, from an 

 acute shoulder surmounted by a single cord ; other spiral sculpture of 

 (on the last whorl nine) widely separated subequal cords on the 

 posterior one of which the suture is laid ; these have the interspaces 

 minutely striated and are not swollen when they pass over the ribs ; 

 axial sculpture of (on the last whorl six) short, very prominent ribs 

 with narrower interspaces, not continuous up the spire and horizontally 

 angulated by the cord which forms the periphery ; they undulate the 

 succeeding suture but are obsolete on the base and anal fasciole; on 

 the early part of the spire the peripheral cord is duplex, but the 

 posterior thread gradually fades out; aperture narrow, anal sulcus 

 deep, rounded, outer lip thin, sharp, arcuately produced; inner lip 

 erased, pillar short, canal very short but distinct. Height of shell, 

 20; of last whorl, 10; diameter, 7 mm. Cat. No. 211649, U.S.N.M. 



Range.— Stditioji 2822, off La Paz, Lower California, in 21 fathoms, 

 sand, U. S. Bureau of Fisheries. 



115690— 19— Proc.N.M vol.56 2 



