160 GAZA. 



muzzle is proportionately shorter than in Gaza, sub cylindrical, 

 granulose at the end, but not laterally expanded. The gill as 

 in Gaza superba, but broader in proportion to its length. The 

 very large anterior lobe of the epipodium is followed by seven 

 gradually decreasing lateral processes, of which five are under the 

 operculum, and are separated by small rounded lobes of the epipo- 

 dial margin. The posterior angle of the epipodium is pointed as 

 in Gaza, extending considerably beyond the operculum, but not as 

 far as the foot. The dentition differs considerably from that of 

 Gaza. It most nearly resembles that of Forskalia declivis Fors- 

 kal, as figured by Troschel (Gebiss d. Schneck., II. pi. xxiv, fig. 

 14.) The rhachidian tooth has a single three pointed cusp, without 

 the accessory denticles of Forskalia, the laterals have two or three 

 accessory denticles, the uncini, unlike Forskalia, are denticulated all 

 along the inner edges of their blade-like cusps, except toward the 

 margin of the radula, where they gradually become simple. It 

 will be observed that in the soft parts there are features which 

 sufficiently distinguish this group from Gaza, according to ordinary 

 standards. 



Subgenus MICROGAZA Dall. 



Microgaza DALL, Bull. Mus. Comp. Zool. ix, p. 50 (1881) ; I.e. 

 xviii, p. 357. 



G. ROTELLA Ball. PI. 48, figs. 5, 6. 



Shell depressed, with five whorls, somewhat flattened above and 

 below ; nucleus small, translucent white, and with the two first whorls 

 polished, smooth or marked only by faint growth lines ; remainder 

 of the whorls with a narrow puckered band revolving immediately 

 below the suture, on which the shell matter is as it were pinched up 

 into slight elevations at regular intervals, about half a millimeter 

 apart. In some specimens, outside of this band an impressed line 

 revolves with the shell ; remainder smooth, shining or with evanes- 

 cent traces of revolving lines impressed from within and strongest 

 about the rounded periphery ; base rounded toward the umbilical 

 carina over which it seems to be drawn into flexuously radiating 

 well-marked plications (about thirty-two on the last turn) which 

 disappear a third of the way toward the periphery ; wall of the um- 

 bilicus concave, overhung by the carina, turns of the shell so coiled 

 that the part of each whorl uncovered by its successor forms a nar- 

 row spiral plane ascending to the apex like a spiral staircase or 



