108 BULLETIN OF THE 



Orbitals. — The junctions of orbitals and cranials are deeply buried in the 

 tissues of the top of the head. The orbital is directed obliquely out toward 

 the eye. In front of the spiracle it passes through the cartilage to the side 

 of the head ; there it makes a shallow backward curve and meets three or four 

 tubes connecting it with the pleural. Eight or ten similar connections are 

 made from the suborbital, behind the point at which it is crossed by the pleu- 

 ral, as the latter passes to the lower (inner) surface between the fin and the 

 skull. The majority of the branches uniting with the pleural below the sub- 

 orbital in reality originated in the suborbital, but in crossing the other tube have 

 become joined to it. After being crossed by the pleural, the suborbital, on its 

 way forward, makes a number of sinuous windings, and sends forth a number 

 of strong many-mouthed tubules, which are nearly parallel as they reach ahead. 

 Anteriorly the tube divides. One section of it passes the edge of the fin to 

 take a course on the inner side along the margin toward the tip; near the latter 

 it turns back, in a slightly sinuous track along the middle of the inner surface 

 of the fin, crossing the pleural, and meets the angular some distance behind its 

 junction with the subrostral. The other section of the suborbital turns toward 

 the rostral, running between it and the edge of the snout. Apparently it con- 

 nects with the rostral, not far from the cranial, and descends, without going as 

 far toward the median line as the former, to meet the extremities of the pre- 

 nasals. The connections and extent of this portion of the suborbital are sub- 

 ject to a little uncertainty on account of the number, excessive delicacy, and 

 confused condition of the tubules, and the preclusion of injections by the 

 preservation of the specimen. The openings of the branchlets of the sub- 

 orbital form an elongate band of pores extending below the eye forward to the 

 upper edge of the fin. 



Nasals. — These are strong transverse tubes ; they become calcified as they 

 approach the median. 



Median. — This tube is elongate, transverse, and, like the nasals, enclosed 

 in a calcified envelope. 



Prenasals. — These are of moderate length, calcified posteriorly, delicate and 

 slender anteriorly, and, apparently, connected in their front extremities by a 

 very slender vessel from the suborbital and rostral. 



Orbito-nasals. — The orbito-nasals are of considerable length, and turn out- 

 ward posteriorly. 



Angulars. — Each angular makes a broad outward curve toward the front 

 margin of the pectoral. 



Orals. — Excessive fineness and delicacy in these vessels makes it ver} r diffi- 

 cult to work them out. They were first sketched from the low ridges formed 

 by the canals on the outer skin. The terminations and finer branchlets, of 

 course, could not be marked in this manner. On removing the skin, however, 

 some of the tubules were lost, and it was found better to give the sketch as 

 taken from the surface. 



