66 BULLETIN OF THE 



Terebra (Acus ?) nassula Dall. 



Plate XXXVI. Fig. 8. 



Shell slender, acute ; yellowish white, or pale buff with the color passing 

 into yellowish white in the region of the sutural band ; whorls eighteen, nucleus 

 inflated, glassy, smooth, few whorled ; remainder of the shell not polished 

 finely, uniformly sculptured ; in the early whorls the band is defined by a 

 constriction in front of the suture, which does not interrupt the sculpture ; as 

 the shell grows this becomes less pronounced and in the later whorls the band 

 is often very feebly defined. The spiral sculpture consists of primary threads 

 and secondary striae ; there are two or three primaries on the band and four to 

 eight on the rest of the whorl, the base being more feebly though similarly 

 sculptured; the spirals override the very numerous close, fine, flexuous trans- 

 verse ribs, there being in these characters the usual tendency to variability in 

 strength, etc. ; the aperture is narrow and elongated with a faint wash of callus 

 on the pillar ; canal short, twisted ; the siphonal fasciole very pronounced, its 

 hinder edge marked with a sharp keel which does not enter the aperture nor 

 appear on the columella. Lon. of shell, 55.0; of last whorl, 16.0; of aperture, 

 10.0 ; max. lat. of shell, 10.0 mm. 



Habitat. Station 32, in 95 fms., Lat. 23° 32' and Lon. 88° 5' W., north of 

 Yucatan in the middle of the Gulf of Mexico ; Station 36, in 84 fms., west- 

 ward of the last, bottom temperature 60° ; Station 206, off Martinique, 

 in 170 fms., sand, bottom temperature 49° ; Yucatan Strait, 640 fms. (ad- 

 ventitious?). 



The only described species which seems at all to resemble this is T. flava 

 Gray, which is an immature shell (referred to the Indo-Pacific T. cancellata 

 Quoy by Tryon) and might be the young of this or a good many other species. 

 T. protexta var. lutescens presents similar characters on a minor scale. 



Terebra (Acus) limatula Dall. 



Habitat. Barbados, 100 fms.; Gulf of Mexico at Station 36, in 84 fms.; 

 Bahamas, west of North Bernini, in 200 fms. (Dr. Rush); U. S. Fish Commis- 

 sion Station 2402, in the Gulf of Mexico, between the delta of the Mississippi 

 and Cedar Keys, Fla., in 111 fms., mud; and Station 2610, 24 miles S. E. 

 from Cape Lookout on the Carolina coast, in 22 fms., sand, bottom temperature 

 79°.0 F. 



The sculpture of Antillean specimens tends to be stronger, the alveoli be- 

 tween the ridges deeper, and the spirals fewer than in the northern specimens. 

 The latter usually have three or four above the suture, the Antilleans two or 

 three. If these differences are worth naming, the variety may be called T. 

 limatula var. acrior. 



