TRACHELIPODA. 79 



Genus 39.— PL Al^ AXIS.— Lamarck 



Generic Character. — Shell ovate or conic, solid; aperture 

 ovate, or somewhat elongated ; colunnella depressed and trun- 

 cated at the base, separated from the outer lip by a compressed 

 sinus ; lip interiorly sulcated, having a callosity running under 

 the superior portion. 



Somewhat allied to the genus Phasianella, but distinguished by the base of 

 the columella being truncated as in the genus Melanopsis. 



Planaxis sulcata — The Furrowed Planaxis. Plate XII. 

 fig. 16. Imperforate, transversely furrowed ; grayish-white, and 

 spotted with black, forming oblique longitudinal fasciae ; outer 

 lip internally crenulated and striated. One inch long. Inhabits 

 the American seas. 



Genus 40.— TURBO.— Zinr.(EM5. 



Generic Character. — Shell conoid, or sub-turriculated ; aper- 

 ture entire, round, margin of outer lip disunited ; columella 

 arcuated, depressed, but not truncated at the base; aperture 

 provided with a testaceous operculum. 



Turbo setosus, — The Bristly Turbo. Plate XII. fig. 17. 

 Thick, transversely and deeply sulcated, and longitudinally stri- 

 ated; spire short; volutions rounded; lip crenulated; varie- 

 gated with white, green, and brown ; inside pearlaceous. Two 

 inches long. Inhabits the Indian seas. 



Genus 4]..— MONODONTA.— Zamarc^. 



Generic Character — Shell ovate or conoid ; aperture round 

 and entire ; outer lip disunited from the body at top ; columella 

 arcuated and truncated at the base ; aperture provided with an 

 operculum. 



Monodonta coronaria. — The Thick-Lipped Monodonta. 

 Plate XII. fig. 10. Covered with numerous, small, scabrous, 

 acute, tubercles ; outer lip very thick ; apex blunt, white ; the 

 columella reddish. One inch and a quarter long. Inhabits the 

 Chinese seas. 



