274 bulletin: museum of comparative zoology. 



with prominent spinulate ridges along suture lines and numerous longitudinal 

 striae. Two antapical spines, 2.5 girdle widths long and 0.7 transdiameters 

 apart, each with hyaline fins which run anteriorly to the girdle. 

 Length 75 n\ transdiameter, 55 y.. 



Sta. 4699. 



Amphidoma Stein. 



The plate formula of this genus is 6', 0°, 6", 6, 6'", 1", 1"". 



Amphidoma curtata, sp. nov. 



Epitheca high, greatly exceeding hypotheca, fuller upon the right side, its 

 altitude 1 transdiameter, its sides convex. Apex truncate, displaced to right. 

 Hypotheca scarcely developed, forming a very low dome, only a girdle width 

 in altitude, fuller upon the right side. Girdle not displaced, slightly impressed 

 no lists. Ventral area acutely indenting epitheca for 0.5 girdle width, extend- 

 ing nearly to antapex without expansion. Plate formula 6 (?), 0°, 6", 6, 6'", 

 1", 1"". Apical 1' slender, reaching to anterior plate of ventral area. Other 

 apicals short, less than 0.25 transdiameter in length; precingular 6" slender, 

 its width 1 and its length 5 girdle widths; postcingular 1'" small, squarish; 

 posterior intercalary and antapical 1"" about equal. Surface finely, faintly 

 and regularly reticulate. 



Length 30 n; transdiameter, 23 p. 



Sta. 4733. 



Amphidoma depressa, sp. nov. 



A minute depressed species, low, top-shaped, with wide intercalary bands. 

 Length equals transdiameter. Body biconical, epitheca exceeding hypotheca, 

 its altitude 0.45 transdiameter, its sides straight, contracted abruptly to a 

 scarcely differentiated apical horn about 0.75 girdle width in altitude. Hypo- 

 theca very low, its altitude 0.35 transdiameter, convex, contracted to a low, 

 obtuse, median antapical horn, 1 girdle width across and 0.5 in length. Girdle 

 not displaced, very slightly impressed, without lists. Ventral area acutely 

 indents the epitheca, passing posteriorly 2 girdle widths with little expansion 

 to an acute end, guarded by low lists. Plate formula 6', a , 6", 6, 6'", l p , 

 1"". Apicals 1', 2', 6' narrow, covering about 0.75 of the apex. Apical 1' 

 asymmetrically diamond-shaped, not fully parting precingular 1" and 6" 

 and scarcely meeting the ventral area; precingular 6" pentagonal; post- 

 cingular 1'" small rectangular; posterior intercalary crowding on to the ant- 

 apex. Surface smooth, except for striate intercalary bands along nearly all 

 sutures in precingular, girdle, and postcingular series. 



Length, 27 y, transdiameter, 27 m- 



Sta. 4733. 



