MUSEUM OF COMPARATIVE ZOOLOGY. 81 



angular the orbito-nasals make an abrupt drop, beyond which they are longi- 

 tudinal. The nasals are long, and have but a small amount of curvature. The 

 median is short, and placed longitudinally. The prenasals aie long, and ab- 

 ruptly bent to the sides to meet the rostrals. Opposite thft nostrils there is a 

 decided outward bend in the subrostrals. 



A great number of long tubules exist on the laterals, and on some of the 

 cephalic tubes. Those from the aural reach directly back. Those from the sub- 

 orbital extend backward or downward; some of them connect with the angular 

 or its tubules ; all are more or less branched. Above the mouth the branches 

 of the angular turn upward ; behind the oral a few of them go downward, 

 where, by meeting others from the oral, and by uniting among themselves, 

 they form a network. On the upper side of the jugular the branches are 

 much more numerous, but have not so many branchlets. Behind the angle 

 of the mouth the tubules of the oral are longer and more branched. 



There is a striking similarity in the canals of Alopias and those of Odontas- 

 pis. This may be seen in cranials, aurals, orbito-nasals, suborbitals, subros- 

 trals, prenasals, nasals, angulars, and orals; and it appears fully to warrant 

 placing these genera side by side in a systematic arrangement of the Galei. 



Heptabranchias. 



- Heptabranchias maculatus (Plate XIV.). On the flanks of this species the 

 canals are shallow furrows, protected by enlarged overhanging scales of the 

 shagreen on the edges. In front the grooves commence above the forward 

 portions of the bases of the pectorals; all the canals farther in front are tubes. 

 Another specimen shows alternation in the lateral, between the aural and the 

 continuous lateral furrow, of irregular lengths of tube and groove. Over the 

 anterior lower lobe of the caudal the furrow bends downward in the direction 

 of the fibrous portion, which it approaches more gradually backward, and it 

 ends at the notch between the lower and the hinder sections of the fin. 



The aural is divided by an interspace, behind the openings of the aqueducts, 

 as in H. pectorosus. A small amount of outward curvature marks the elongate 

 occipitals. At each side of the fontanelle the cranials bend out in a broad 

 curve toward the side of the head. In front of the nostrils the rostrals turn 

 back toward the subrostrals, but apparently without meeting them. These 

 tubes seem to be separated, just above the nostril, by a short interspace. On 

 the top of the head, again, the orbital is directed outward and a little forward-; 

 on the side it goes down and backward, without forming a suborbital, to join 

 the angular and orbito-nasal. The latter is very long, and takes the place 

 of the suborbital. Jugular, angular, and orbito-nasal form a single longitudi- 

 nal line; the first is short, ending in front of the middle of the first gill cleft, 

 the second is of moderate length, and the third is as long as both of the others. 

 The nasal is of moderate length, curves strongly toward the median line, but 

 does not meet its fellow, from the other side, to form a median. The pre- 

 voi. XVII. — Ko. 2. 6 



