44 PROCEEDINGS OF THE KATIOXAL MUSEUM. vol. 37. 



tooth-bearing border is arched, while the opposite border is slightly 

 concave in each direction from near the middle of the length. A 

 transverse section (text fig. 1) taken between the 

 first and second teeth, connting from the right, 

 shows that the lower border is here broadly 

 rounded, while a section (text fig. 2) across the 

 liinder half of the fossil shows that there the 

 lower border is acute. Beginning just in front 

 of the first tooth a sharj:) and narrow groove 

 runs along the midline of the specimen, widen- 

 ing at the front end, then contracting and run- 

 ning backward on the lower side (text fig. 1, 7) 

 to near the middle of the length. 

 , „' Along the upper border of the fossil are six 



Fig. 1. — Edestus cren- & i i 



uLATus, XI. TYPE, compresscd teeth, the anterior and posterior. 

 VERTICAL SECTION BE- jjordcrs of whlch are furnished with denticles. 



TWEEN THE FIRST AND 



SECOND TEETH. 2. Of tliesc dcnticlcs there are 8 or 9 on the anterior 

 SECOND sheath; 2\ Q(\frQ and perhaps 1 or 2 fewer on the hinder 



ENAMELED PROCESS OF '^ ^ i 



SECOND tooth; 3, edge. Each of these denticles is minutely cren- 

 In^r^ «L/"'"'' "lated. Each tooth is covered by a layer of 



tooth ; 4, sheath of • "^ 



FOURTH tooth ; 5, enamel, and at the base of the tooth a process 

 SHEATH OF FIFTH ^f ^j^j^ euamcl ruus forward beneath the hinder 



tooth ; G, UPPER BOR- 

 DER OF SHEATH OF third of tlic ucxt tooth in 

 SIXTH tooth; 7, j^^|^.„-,(.p ^he following 



GROOVE along LOWER _ _ . *^ 



BORDER OP ANTERIOR figurcs giYQ tlic dimcnsious 



HALF OF SHAFT. ^f ^J^^ ^^^^^^ rj^j^^ ^^^^^^^ "^ 



taken from the point where the tooth joins the 

 one in front to its contact Avith the next behind. 

 The height is from the apex to the lower border 

 of the enamel, along the axis. Tooth, 1 ; length 

 of base, 26 mm.; height, 19± mm.: tooth, 2; 

 length of base, 27 mm.; height, 19± mm.: tooth, 

 8; length of base, 27.5 mm.; height, 19 mm.: 

 tooth, 4; length of base. 28 nun.; height, 19± fig. s.-edestus cren- 



1 ^ „, ^ . ^ ULATUS, X 1. TYPE. 



mm. : tooth, 5 ; length of base, 30 mm. ; height, vertical section be- 

 19 ± mm.: tooth, 6; length of base, 30.5 mm.; ^ween third and 



... ' <=> FOURTH teeth. 3, 



lieigut, lo± mm. hinder end of third 



The thickness of most of the teeth at the lower ^ooth ; 4, sheath 



, J. , . . mi r. -Til •''■' FOURTH tooth; 4^ 



end or the axis is 8 mm. 1 he first one is slightly enameled process of 

 less ; the last one is only 6 mm. thick. The angle fourth tooth ; r.. 

 between the anterior and posterior borders of tooth ; 6. upper bor- 

 any tooth is very close to 90°. It will be observed ^i=« '^^ sheath of 

 that the hinder tooth descends to the lower 

 border of the shaft. The surfaces of all the teeth are smooth. A 

 number of cracks in the enamel pass from the base of each tooth to 

 the apex, and these seem to follow slight ridges. 



