284 bulletin: museum of comparative zoology. 



Heterodinium angulatum, sp. nov. 



Bears a general resemblance to H. hindmarchi f. maculata Kofoid (1907), 

 pi. 7, fig. 42, but differs in having both shoulders angled, the excavation 

 between the antapical horns wider and less arched, the surface more coarsely 

 reticulate. Length 1.33 transdiameters on anterior girdle list. Epitheca 

 exceeds hypotheca, both shoulders almost right-angled, abruptly contracted 

 to tapering apical horn. Hypotheca with symmetrical, slightly incurved, 

 tapering, obtuse antapical spines, with the arched postmargin flattened in the 

 central part. Anterior girdle list salient, shelf -like, posterior deficient. Sur- 

 face very coarsely reticulated with irregular, porulate polygons. Wide 

 intercalary bands smooth, or wholly, or partially reticulate with fine quad- 

 rangles. 



Length, 85 n; transdiameter, in girdle, 50 /i, on anterior ridge, 60 n. 



Sta. 4691. 



Heterodinium elongatum, sp. nov. 



A small species of elongated form, coarse reticulations and small, close set 

 antapical horns, somewhat resembling H. hindmarchi Murray and Whitting 

 (1899), pi. 29, fig. 1, but relatively longer and with smaller, sharper, closer set 

 antapical horns. Body elongated, its length twice the transdiameter in girdle. 

 Epitheca slightly exceeds hypotheca, conical, with obliquely truncate apex 

 but no apical horn, its sides nearly straight. Hypotheca more angular, 

 antapical horns symmetrical, their length a little less than 0.25 and the dis- 

 tance between their tips 0.42 transdiameter in girdle. Girdle descending, 

 displaced 1 girdle width, without overhang; excavated beneath epitheca, 

 posterior list feebly suggested by salient angle. Ventral area contracted 

 anteriorly, spreading abruptly into shovel-shaped area, terminating at post 

 margin which is denticulate. Surface coarsely reticulate with large, irregular 

 polygons, sutures marked by ridges. 



Length, 68 /z; transdiameter, in girdle, 35 n, on anterior ridge, 44 /*. 



Sta. 4732. 



Heterodinium laeve, sp. nov. 



A large, smooth species with oblique girdle, dorso-ventrally flattened body, 

 low epitheca, with unequal, asymmetrical antapical horns curved to the left 

 and ventrally, somewhat resembling H. inequale Kofoid (1906), pi. 18, figs. 9, 

 10, but differing in greater asymmetry, and longer more curved antapical 

 horns. Length, to middle of antapical margin, 1.18 transdiameters. Epi- 

 theca low, its middorsal altitude 0.32, and midventral 0.27 transdiameter, 

 its anterior outline nearly semicircular, apical area to the right, ventral pore 

 swung far to the left. Girdle plane oblique, passing from dorso-anterior 



