148 REVISTA CHILENA DE HISTORIA NATURAL 



broad and marked by rather wide dental ridges. of which 

 25 occur in a line parallel to the ventral margin of the 

 anterior part in the type. These ridges bear strong den- 

 ticles which bave minor cusps at the free margin. The 

 dental ridges join those of the anterior part at a little rao- 

 re than a right angle. The median portion of the middle 

 part is crossed by obliquely slanting, rough, irregular 

 lines. The posterior portion of the median part is weakly 

 rounded and marked by concentric lines of gro^Yth, which 

 are not particularly prominet. The posterior párt forms a 

 slender auricle, which is separated from the posterior 

 portion ef the median part by a strong constriction. The 

 posterior part of the auricle in the type ie eroded, but in 

 spite of this we may say that the auricle is quite small. 

 The interior is white, excepting the anterior and anterior 

 median portions, which are brownish. The junction of the 

 anterior and median part is innicated by a tumid ridge. 

 The middle median portion beare a series part is indicated 

 by a tumid ridge. The middle median portion bears a se- 

 ries of scallops and is rather roughened. The posterior 

 part or auricle forms a shelf which extends from the um- 

 boue two-thirds of the way to the ventral margin and has 

 a hollow cavity behind it. It does not project materially 

 outward. The umbones are not very heavy and from their 

 under side the oblique narrow, curved blade extends two- 

 thirds of the way across the shell. The ventral median 

 portion bears a weak knob. The pallets are typically those 

 of Bankia s. s., that is, they consist of a series of cone-in- 

 cone shaped elements, each with a strong awnlike projec- 

 tion at its lateral margin and a thin, fimbriated membra- 

 ne that extends across the entire pallet, and is particu- 

 larly conspicuous on the outside. At their free margin the 

 individual elements of these pallets form a concave curve 

 on the outside and a double curve on their inner margin, 

 whit a modérate sinus in the inner middle portion. 



The type, Cat. N.° 348,498, ü. S. N. M., comes from 

 Chiloé Island. Tt measures: height, 6 mm.; length, 5.8 

 ram.; diameter, 5.8 ram. The pallets meausure; lenght, 21 

 mm., ofwhichG mm. go to the stalk; width of pallet 

 3. 2 mm. 



When com pared wih Bankia {Bankia) setacea, the 



