294 bulletin: museum of comparative zoology. 



times that of same diameter distally. Branches, seen in lateral view, 0.33, 

 0.25 and 0.18 of total length in length. Axis straight in direct lateral view. 

 Flagellar pore 0.09 of total length from head. Head thin, flat, its length 

 equalling greatest width of midbody, and five times that of neck. Fins wide, 

 ribbed. Ant apical region curved to left and vent rally, with curved foot-like 

 ant apex bearing stout spine at heel and two distally. 

 Length, 790 yu; dorso-ventral diameter, 45 n. 



Sta. 4695. 



Amphisolenia truncata, sp. nov. 



Body in lateral view rectilinear. Length forty times greatest dorso-ventral 

 diameter. Slenderly fusiform, greatest dorso-ventral diameter one third of 

 total length from head, about twice dorso-ventral diameter of antapex, dimin- 

 ishing very gradually in either direction. Flagellar pore removed from apex 

 0.11 of total length. Head thin, flat, elevated 40° from horizontal, furrow 

 sparingly and coarsely ribbed, lists hyaline, without ribs. Antapex in lateral 

 view rectilinear and squarely truncate, without spines, lists, enlargement, 

 or asymmetry. 



Length, 640 y.; dorso-ventral diameter, 16 p. 



Sta. 4733. 



Histioneis diomedeae, sp. nov. 



Belongs to the para group, with stout, posteriorly curved extension of the 

 midbody at base of anterior collar. Most resembles H. reticulata Kofoid 

 (1907), pi. 15, fig. 95, but differs from it in being much larger. The measure- 

 ments given (1907, p. 205) for this species should read, length, 57 ju; dorso- 

 ventral diameter (total) 42 ju. It has also an entirely different outline in 

 dorsal view. In H. reticulata the midbody has nearly a semicircular posterior 

 outline; in H. diomedeae the body is laterally contracted giving to the antapex 

 concave sides and a blunt prolongation, in the dorsal view. In H. reticulata 

 the midbody is abruptly angled at the junction of the posterior collar and in 

 lateral view this line forms a sweeping curve. In H. diomedeae the sides, in 

 dorsal view, slope regularly at an angle of 45° and the line of junction in lateral 

 view shows a median elevation. Length of midbody 1.08 its dorso-ventral 

 diameter. Transdiameter 0.7 dorso-ventral, epitheca 0.52, horn 0.45 dorso- 

 ventral diameter. Anterior collar sessile, 0.78 dorso-ventral diameter of 

 midbody from dorsal to ventral lip, with numerous simple ribs and marginal 

 riblets. Posterior collar almost same diameter as midbody, bagging out 

 slightly along lateral line of attachment, 0.35 dorso-ventral diameter in 

 height, lightly reticulate on dorsal and ventral regions, with dorsal and ventral 

 ribs only. Ventral fin somewhat as in H. garretti Kofoid, but its margin with a 

 protruding, bluntly rounded point at the fission ribs, and concave thence to- 



