400 Bulletin American Museum of Natural History. [Vol. XIX, 



some doubt regarding a small patch of scales seen there. 

 Measuring from the mouth to this patch of scales, which 

 appear to form the tip, the distance is 150 mm. The borders 

 of the rostrum have been straight or slightly convex. At 

 50 mm. in front of the mouth the width of the rostrum is 

 50 mm.; at a distance of 100 mm. the width equals 35 mm. 

 Beyond this the rostrum appears to have narrowed somewhat 

 more rapidly. A glance at the rostrum described by Dr. 

 Woodward shows that it was of a different form, the lateral 

 borders being concave. In 5. solomonis, at a point 45 mm. in 

 advance of the mouth, the head begins to expand rapidly, so 

 that at a line slightly in front of the mouth the width is 100 

 mm. In 5. atavus the width in a corresponding position 

 could not have been more than 75 mm. 



The preservation of the rostrum is due to its being com- 

 posed of a mosaic of minute hexagonal calcifications, such as 

 we find in the same cartilages of Pristis. If there was a 

 shagreen overlying these cartilages, it does not now show 

 itself. A stellate shagreen is present along the sides of the 

 head as far forward as where these join the rostrum. Over 

 the base of the fin rays the shagreen scales are polygonal, con- 

 vex, smooth, and enameled. 



The rostral teeth of this species are quite different from 

 those of 5. atavus, in size at least. The longest of those rep- 

 resented in Dr. Woodward's figure are 7 mm. long, and there 

 are about 4 of them in a distance of 10 mm. In S. solomonis 

 there are no teeth more than 3 mm. long, and there are 8 of 

 them in 10 mm. These teeth have a stellate base, as in S. 

 atavus, and they appear to have been directed somewhat 

 backward. For some distance beyond the base, for one third 

 or one half of its length, the tooth is terete; then the diameter 

 is suddenly increased, forming a sort of shoulder. The re- 

 mainder of the tooth is gently curved backward, slightly flat- 

 tened, and brought to an edge on the convex border. It is 

 apparently only the distal portion of the tooth which is 

 enameled. Toward the extremity of the rostrum the teeth 

 are somewhat smaller. Posteriorly, the teeth become very 

 small and are hardly to be distinguished from some of the 



