298 bulletin: museum of comparative zoology. 



HlSTIONEIS KARSTENI, Sp. 110V. 



A small species resembling H. para Murr. and Whitt. (1S99), pi. 32, fig. 4, 

 but much smaller, with narrower, more ventrally located, broadly rounded 

 apical projection, smaller anterior, and non-ribbed posterior collar, and 

 greater dorsal and posterior development of the sagittal fin. Body very 

 rotund, with bluntly and symmetrically rounded anterior projection on 

 epitheca, 0.3 dorso-ventral diameter in height and of the same width. Length 

 1.1 dorso-ventral diameters. Anterior collar sessile, with 7 heavy ribs, its 

 height about 0.25, and opening 0.82 dorso-ventral diameter. Posterior 

 collar of same diameter as midbody, its height dorsally 0.55 dorso-ventral 

 diameter, with dorsal and ventral vertical ribs but no other markings. Ventral 

 fin low, heavily reticulate, fission ribs 0.25 dorso-ventral diameter in length, 

 slanting at 45° from horizontal. Posterior fin with median posterior spine 

 0.66 dorso-ventral diameter in length. Fin terminating acutely, with arched 

 postero-ventral and sigmoid dorsal margins, faintly reticulated on both sides 

 of spine and extending dorsally at base beyond spine 0.27 dorso-ventral 

 diameter. Surface of midbody coarsely and deeply reticulated, 15 meshes 

 behind girdle. Scattered pores. 



Length, of midbody, 28 /x, total, 56 n; dorso-ventral diameter, of midbody, 

 26 m, total, 30 /x. 



Sta. 4619. 



HlSTIONEIS PANDA, Sp. IIOV. 



A medium sized species resembling H. navicula Kofoid, but smaller, with 

 more concave midbody, smaller inner collar, and laterally expanded posterior 

 collar. Body greatly elongated dorsally, with deeply concaved anterior and 

 convex posterior surfaces, the depth of the concavity equalling the antero- 

 posterior thickness of the middle of the body. Body somewhat expanded 

 dorsally. Distance between dorsal and ventral ends 4 times thickness of 

 middle and 2 times its antero-posterior extent. Anterior collar elongated, 

 slender, its height equalling, and apex 0.4 of dorso-ventral extent of midbody. 

 The apex is very oblique, notched on left ventral margin. Posterior collar 

 also with oblique, but contracted opening, about 0.5 of dorso-ventral extent 

 of midbody, expanding dorsally. On the lateral faces spreading horizontally 

 nearly 0.33 of dorso-ventral extent of midbody in saddle-bag fashion. Dorsal 

 ribs low, horizontal bars, sinuous, sagged posteriorly. Both collars faintly 

 reticulate with polygonal mesh antero-dorsally. Ventral fin very low, its 

 ventral margin vertical, straight. Fission ribs directed posteriorly, 0.33 

 dorso-ventral extent of midbody in length, posterior member continuous by 

 marginal arch with short posterior spine, the arch pinnate. The fin extends 

 posteriorly 0.55 dorso-ventral extent of midbody, and its dorsal frill is ventrally 

 protruded as in H. pulchra Kofoid. Surface smooth, a double row of pores 

 along junction of posterior collar. 



