86 BULLETIN OF THE 



other tubes ; a short distance in front of their ends are those of the orbitals, 

 also disconnected; and still farther in front are the posterior extremities of the 

 cranials, like the others, making no connections. The orbitals pass directly 

 outward, then downward and forward, meeting the angular below the hinder 

 portion of the eye. At the start the cranials are transverse, they soon bend 

 forward, and, making very open curves around the fontanelle, becoming ros- 

 trals, converge toward the end of the snout, before reaching which they pass 

 through to the lower aspect. As subrostrals they go back and outward , mak- 

 ing a loop on the side and top around the nasal chamber, and pushing farther 

 back to meet the nasals. In comparison with that of other genera, the orbito- 

 nasal is rather long; it extends below the greater portion of the orbit. A 

 prominent curve toward the nostril marks the middle of each of the elongate 

 transverse nasals. From a median of more than ordinary length the prenasals 

 diverge and run forward, ending abruptly, under the tip of the snout, without 

 joining the rostrals. The angulars are of moderate length. The jugular is 

 short. An oral could not be found. The tubules are numerous, short, and 

 provided with large apertures. 



Especially noticeable among the pecv;liar features met with in this species are 

 the separation of the orbitals and the cranials from the occipitals, the isolation 

 of tlie prenasals, the supranarial curve of the subrostrals, the length of the 

 orbito-nasal, the lack of tlie oral, and the caudal curve of the lateral. The 

 coronal arrangement of the ceplialic canals, and the subrostral curve, distin- 

 guish the genus from any of the other genera noted here. The orbito-nasal and 

 the disposition of the lateral on the tail are intermediate between sharks like 

 Heptabranchias and the majority of those of higher rank. In Cestracion (Zy- 

 gsena) only of the other Galei have we seen the subrostral return to the top 

 of the snout. 



Rhina. 



Ehina squatina (Plate XXL). With the great depression of the body of 

 this Shark, the lateral has to some extent been carried outward on the thoracic 

 and the scapular regions. Excepting slight waves in the outline, there is 

 hardly a deviation from a straight line in the tubes on the sides of the tail. 

 The canal does not reach quite to the hindmost vertebra. Above the thoracic 

 region near the aural a few of the tubules reach toward the median line. 

 Elsewhere along the whole length of the laterals the tubules are short and 

 directed out. 



In consequence of the anterior position of the mouth and the shortness 

 of the snout, the canals of the front part of the head are greatly reduced in 

 length. Subrostrals, prenasals, and otlier tubes that in the balance of the 

 Sharks are confined to the lower surface, have T)een brought to the top by de- 

 pression of the head. The aural is long, curves backward slightly, and has 

 a few tubules extending toward the shoulders. The occipitals are long, and 

 <livergent forward. On the frontal region, the cranials curve toward each other; 



