276 bulletin: museum of comparative zoology. 



Amphidoma obtusa, sp. nov. 



Body less elongated than in A. acuminata, antapex broadly rounded. 

 Length 1.42 transdiameters. Epitheca conical, sides scarcely convex, its 

 altitude 0.6 transdiameters, equalling hypotheca. The latter with nearly 

 straight sides and very broadly rounded antapex. Girdle very shallow, 

 descending, displaced 0.3 girdle width. Ventral area straight, extending 

 posteriorly barely 2 girdle widths to asymmetrically rounded end, scarcely 

 impressed. Plate formula 6', 0°, 6", 6, 6'", l p , 1. Apical 1' asymmetrically 

 diamond-shaped, extending posteriorly to ventral area; the other apicals 

 shorter, nearly twice the length of the precingulars; precingular 6" squarish; 

 postcingular 1'" minute, subtriangular; posterior intercalary wide, 1.5 by 

 2 girdle widths. Surface smooth, faint intercalary band at apical-precingular 

 suture. 



Length, 27 n] transdiameter, 18 m- 



Sta. 4720. 



Goniodoma Stein. 



Theca composed of three apicals, V to 3', about a depressed closing platelet, 

 no anterior intercalaries, seven precingulars, 1" to 7", six girdle plates, 1 to 6, 

 plus two additional platelets in region of ventral area, five postcingulars, 1'" 

 to 5'", no posterior intercalary, and three antapicals, 1"" to 3"". The ventral 

 area is made up of five platelets in addition to the two in the level of the girdle. 



Goniodoma reticulata, sp. nov. 



A small spheroidal species with porulate epitheca, and hypotheca very 

 irregularly covered with a coarse, heavy but imperfect reticulum. Differs 

 from G. acuminata var. tener Schiitt (1895) pi. 7, fig. 31, in structure at girdle 

 junction and in surface markings. Body spheroidal, length 1.1 transdiameters. 

 Epitheca exceeds hypotheca, its altitude 0.65 transdiameter, hemispherical, 

 spreading somewhat at the girdle, apical area not projecting. Hypotheca 

 depressed hemispherical, its altitude 0.4 transdiameter. Girdle postmedian, 

 descending, displaced one girdle width, distal end curved posteriorly, impressed, 

 with low, hyaline, irregularly ribbed lists. Ventral area short, 3 girdle widths 

 in length and 1.5 in width, arched to the right, with spinous lists on either side. 

 Apical area triangular with elliptical pit. Ventral pore in anterior margin of 

 precingular 1". Antapicals 1"" and 3"" small, unequal, 1"" much like a 

 posterior intercalary of Gonyaulax. Antapical 2"" large, quadrangular. 

 Surface of epitheca irregularly marked with areoles of various sizes. Hypo- 

 theca with loose, imperfectly anastomosing mesh work. 



Length, 40 n] transdiameter, 36 ix. 



Sta. 4722. 



