296 bulletin: museum of comparative zoology. 



margins, its length, from lip of posterior collar, 3.35 times longer axis, its 

 greatest width at level of postmargin of midbody 0.8 of longer axis. Fission 

 ribs 0.5 of longer axis in length, at 40° from horizontal. Fin with distal, 

 transverse lattice between marginal ribs. Phaeosomes very large, spheroidal 

 and minute ellipsoidal. 



Length, of longer axis, 26 n, total antero-posterior of midbody, 26 n, of 

 whole organism 115 ju; greatest dorso-ventral extent 38 m! phaeosomes, 

 spheroidal, 5 n, ellipsoidal, 0.5 by 1.2 p. 



Sta. 4722. 



HlSTIONEIS HIPPOPEROIDES, sp. IIOV. 



Resembling H. reginella, sp. nov. but with larger midbody, lateral pouches 

 less developed, not reticulated distally, and anterior collar not widely dilated 

 distally. Midbody enlarged postero-dorsally, to twice its antero-posterior 

 thickness ventrally, deeply concaved in the middle, the dorsal hump slightly 

 higher than the ventral. Collars and fins much as in H. gubemans Schiitt 

 (1895), pi. 5, fig. 23, except that they are larger and more reticulated and the 

 inner collar tapers gradually to a small oblique opening only 2.2 its diameter 

 at midbody, with very little distal flare. The outer collar has lateral exten- 

 sions (saddle bags) between the horizontal bar and the midbody, the total 

 transdiameter through them being 1.5 transdiameters of the midbody. This 

 collar is covered with a coarse network beyond the horizontal bars, in which 

 a second distal encircling bar is irregularly outlined. The ventral fin extends 

 postero-ventrally, the fission ribs and the posterior rib being subparallel and 

 at 30° and 40° respectively from the horizontal. It bears a marginal band of 

 elongated reticulations and coarser inner network. The ventro-posterior 

 spine bears a transverse fin as in H. dolon Murr. and Wliitt., somewhat wider 

 than the midbody. 



Length, antero-posterior, of midbody, 30 n, total, 90 n; dorso-ventral 

 diameter, of midbody, 37 ju, total, 68 p. 



Sta. 4590. 



HlSTIONEIS HYALINA, Sp. I10V. 



A small species of simple structure resembling the less developed forms of 

 H. cymbalaria Stein, but much smaller and with midbody of different shape. 

 Midbody pyriform with long axis horizontal, but slightly concave anteriorly 

 and enlarged dorsally, its dorso-ventral diameter 1.8 times its greatest antero- 

 posterior one. No elevation at base of inner collar. Collars as in simplest 

 form of H. cymbalaria as figured by Stein (1883), pi. 22, fig. 10, complete 

 hyaline extension beyond horizontal ribs, and with a single bifurcated vertical 

 spine in addition to the dorsal and ventral ones. Inner collar with dorsal 

 flare, reticulate distally. Ventral and posterior fins as in H. cymbalaria except 



