228 BEV. R. BOOG "WATSON ON THE 



a little rounded, slopingly shouldered above with a broad open 

 labial sinus. Sculpture. There are very faint sharp curved lines 

 of growth, strongest, as usual, on the base. Spirals — besides the 

 bluntly angulated and slightly swollen basal carina, which appears 

 as a slight projection above the suture at the base of each whorl, 

 there are two threads whose prominence slightly carinates each 

 whorl ; they nearly trisect the whorl, but that the highest is a 

 little more than a third of the whorl's height below the suture. 

 There is another thread as broad, but less prominent, halfway 

 between the lowest carinal thread and that above the suture ; 

 another, narrower, appears less than halfway between the upper 

 carinal thread and the suture. On the upper whorls the upper 

 carinal thread becomes much the most dominant and angulates 

 the whorls. Besides these, the surface is closely covered with 

 unequal, fine, flat-topped threads parted by very narrow square- 

 cut furrows. There are of these threads about fifty above the 

 basal carina of the last whorl. On the base there are about the 

 same number, or rather more, of similar threads ; but the furrows 

 are opener and shallower. Of these basal threads some six or 

 seven are rather stronger than the rest. They are all a little in- 

 terrupted on the base by the radiating lines of growth. Besides 

 these lines, the whole surface is exquisitely fretted with delicate 

 close-set, microscopic spirals, of which about four go to yjtwu ^ n -» 

 and much more coarsely scored with longitudinal bars (about one 

 thousandth of an inch apart), which in the furrows of the larger 

 system of spirals appear like the sharp edges of very thin lamella?, 

 and which are probably in some way connected with the epidermis 

 of the shell. The whole of this microscopic system of sculpture 

 is present on the base. Colour porcellanoiis white, irregularly 

 stained with suffused streaky blotches of ruddy brown, which 

 appears as minute sparse specks on the carinal threads and on the 

 base. Spire is high, narrow, and slightly scalar. Apex is broken. 

 Whorls. There have evidently been 16-17 (but the first two or 

 three are gone), of very regular increase ; a few near the apex are 

 angulated in the middle, but all the others are concavely and 

 slopingly shouldered below the suture, somewhat straight in the 

 middle, and slightly contracted below, where they project a very 

 little at the suture beyond the top of the succeeding whorl. The 

 edge of the slightly concave and barely conical base is right- 

 angled. Suture defined only by the small ledge which projects 

 above it. Mouth square, bluntly pointed above, and rounded on 



