MUSEUM OF COMPARATIVE ZOOLOGY. 83 



extend forward with a very slight trend outward. On the crown the cranials 

 are parallel. At the sides of the fontanelle they hend abruptly outward, and, 

 as rostrals, run near the edge of the snout for some distance before going to the 

 lower surface. From the cranials the orbitals run outward and somewhat for- 

 ward; near the side they turn backward and downward toward the corner of 

 the mouth. They end some distance behind the eyes. A long angular joins 

 the short jugular and the very long oral, which reaches almost to the sym- 

 physis. At the end of the jugular near the middle of the first branchial aper- 

 ture, there are two branches not found in any other of the Sharks examined: a 

 spiracular (sp), turning upward and forward toward the spiracle, and a gular (g), 

 turning down and forward near the median line, and finally uniting with the 

 oral a short distance from the inner end. Below the eye, in the position usu- 

 ally occupied by the suborbital, lies a very long orbito-nasal. The nasal is of 

 moderate length, and curves broadly in its posterior half. The subrostral is a 

 little shorter than the nasal; it bends upward over the nostril. Apparently 

 the prenasal is reversed in direction, meeting the nasal in front and running 

 backward to join the subrostral. Like the corporals, oral, gular, and spiracu- 

 lar are open grooves. In the spiraculars and gulars of this Shark are found the 

 nearest approaches to the pleurals of the Batoidei. 



Distinguishing peculiarities of the system on this type are seen in the pos- 

 session of spiracular and gular canals, in the position of the prenasals, and in 

 that of the aural, with regard to the ear openings. Similarity in the orbito- 

 nasal occurs in Heptabranchias. Somniosus by the same canals is interme- 

 diate between these genera and others of the order. 



Ginglymostoma. 



Ginglyrnostoma cirratur.% (Plate XVI.). Over the shoulders the laterals have 

 little outward curvature; in the anterior part of the tail they drop somewhat 

 abruptly from the middle to the lower portion of the muscular band, near the 

 edge of the fin, where they continue, ending with the vertebral column. 



This form has a short broad head, and a very short snout. If compared 

 with one of the long-snouted species, it will be seen that there is a tendency 

 toward the transverse in the cephalic canals, which in those forms are nearly or 

 quite longitudinal. The aural is long, bending backward a little in the middle, 

 and as much forward toward each end. The occipital is of medium length; it 

 runs obliquely outward, with a slight curve toward the spiracle in the middle. 

 From the end of this canal the cranial turns rather sharply toward the crown; 

 it then passes forward, diverging a little from its fellow until opposite the fonta- 

 nelle, where it turns outward with less curvature than in Scylliorhinus. Ap- 

 proaching the edge, the rostrals run parallel with it until near the tip, where 

 they descend. The orbital is rather short. The suborbital is much longer and 

 passes forward more than three times the diameter of the orbit; above the nos- 

 tril it turns back, forming an angle, and meets the subrostral a short distance 

 forward from the. eye. Angular and jugular are short; they are directed up- 



