206 BULLETIN : MUSEUM OF COMPAEATIVE ZOOLOGY. 



Ornithocercus heteroporus, sp. nov. 



Plate 13, Fig. 70. 



A minute species with slightly oblique axis, relatively few ribs in the collar, 

 posterior wing confined to the ventral side of the midbody, with marginal ribs. 

 Pores heterotypical. 



Midbody rotund, laterally compressed, its length 1.16 times the dorso- 

 ventral and 1.3 times the transverse diameter. Anterior collar flaring with 

 few ribs, reticulated basally. Posterior collar with 8 ribs, a row of coarse 

 reticulations at its base and along the base of the right ventral wing (obsolete 

 in individual figured). Left ventral reticulate at base. Posterior wing con- 

 fined to ventral side with marginal ribs and peripheral seam. Thecal wall 

 porulate with evenly distributed pores, one in 6 or 8 darker than the others. 



Length, 50 fi ; dorso- ventral diameter, including fin, 37 /x. 



Station, 4699. 



Ornithocercus serratus, sp. nov. 



Plate 15, Fig. 93. 



A large species with rounded posterior wing with 4-5 equidistant rounded 

 or acute apices. 



This species differs from all others in the large number and the regularity 

 of the marginal prominences of the posterior wing, each of which is the termi- 

 nation of a single rib. There is as a rule no marginal connecting rib as often 

 in 0. rnagnificus, steini, and quadratus. The dorsal margin of the posterior 

 wing is more rounded, not angular or squarish as in other species. The ribs 

 are also more regularly spaced, freer from branching and other irregularities, 

 and the posterior wing has less intercostal reticulation. Terminal reticular 

 brushes appear on some individuals at the ends of the ribs. 



Length, 110-145 ft ; dorso-ventral diameter, 95-130 fi. 



Stations, 4613, 4742. 



Amphilothus quincuncialis, sp. nov. 



Plate 1, Fig. 10. 



A minute species of ellipsoidal form, median girdle, with skeletal elements 

 with quincuncial arrangement in the hypotheca. 



Body broadly ellipsoidal, its length 1.6 times the transverse diameter. 

 Epitheca and hypotheca subequal. Epitheca a low cone with very constricted 

 blunt apex, its altitude 0.8 of its transdiameter. 



Hypotheca a low dome with very broadly rounded antapex, its altitude 0.8 

 times its transdiameter. 



Girdle 0.1 of the total length in width, nearly median in position, deeply 

 impressed, without lists, horizontal, without displacement. Longitudinal 

 furrow straight, a wide shallow furrow, 0.8 of the length of the body in 

 length, equally extended on the two sides of the girdle. 



