300 bulletin: museum of comparative zoology. 



HlSTIONEIS STRIATA, sp. nOV. 



Resembling H. gubernans Schiitt but differing from his (1895), pi. 5, fig. 23, 

 in its smaller size, much smaller collars, and proportions of ventral fin. Mid- 

 body rotund, more symmetrical than in H. gubernans, postero-dorsal concavity 

 well developed, horizontal, its length 0.55 dorso-ventral diameter. Length 

 0.92 dorso-ventral diameter. Anterior collar elongated, its length 1.2 and 

 opening 0.3 dorso-ventral diameters, neck stout, opening oblique, with several 

 distal riblets. Posterior collar not so wide as midbody, its height 0.9 to 1 

 and its opening 0.85 transdiameter, constricted dorsally at level of arched 

 horizontal bars, its distal frill high, with about 6 vertical distal riblets on each 

 face. Ventral fin as in H. gabernans and H. reginella. Marginal rib with 

 distal frill and scattered distal riblets. Post ero- ventral spine horizontal, 

 distally recurved, the fin upon its dorso-posterior margin recurved ventrally 

 as in H. reginella. Surface smooth, 7 pores behind posterior collar and 3 

 midway below. Phaeosomes ellipsoidal. The distal riblets of the collars 

 and fins give the organism a striate appearance. 



Length, of midbody, 15 n, total, 42 /u; dorso-ventral diameter, of midbody, 

 16 n, total, 31 n; phaeosomes, 1 by 1.5 m- 



Sta. 4720. 



Ornithocercus formosus, sp. nov. 



A large and handsome form not closely resembling any known species. 

 General outline of whole in lateral view rectangular with concave postmargin. 

 Body subcircular in lateral view, fuller in postero-dorsal region. Squarish 

 toward the girdle, its length about equal to its dorso-ventral diameter. Trans- 

 diameter 0.7 dorso-ventral. Anterior collar 0.83 dorso-ventral diameter, 

 with simple ribs mostly complete, with reticulate mesh near base. Posterior 

 collar basally expanded, with stouter ribs and heavy reticulations reaching 

 margin in dorsal and ventral quadrants. Ventral fin running straight poste- 

 riorly from lip of posterior collar, with coarse irregular reticular mesh filling 

 the fin and also the minor right fin which is short and rectangular in form. 

 The postmargin of the sagittal fin is crescentic with feebly developed marginal 

 rib, nearly submerged radial riblets and a very stout dorso-posterior spine 

 in the dorsal lobe of the crescent with fine mesh on its dorsal wing. Dorsal 

 margin straight. Surface regularly and deeply pitted with porulose pits. 



Length, of body, 40 /x, total, 90 ju; dorso-ventral diameter, of body, 40 ju, 

 total 50 to 63 m- 



Sta. 4697. 



Ornithocercus orbiculatus, sp. nov. 



A large species resembling 0. serratus Kofoid, but with entire, orbicular, 

 sagittal fin. Body subcircular in lateral view, obliquely flattened anteriorly 

 and excavated antero-dorsally. Its length a trifle less than its greatest dorso- 



