STEWART: VARIATIONS IN THE GENUS XIPHACTINUS LEIDY. iL ale7/ 
“‘The dentary is similar in form to that of P. molossus, but rather 
more numerous teeth. Counting from the front, there are two 
large, one rather small; two large, and eighteen small and medium 
following; the smallest from third to ninth, inclusive. The alveole 
are nearly round.”’ 
Below is given a table showing the arrangement of the teeth in 
the specimens under consideration: 
MANDIBLES. 
Sinatra foi Oe ae Srna. os 
I, 2 : ) 5 SF g I 20 
2, 2 I I 8 12 ae ae 24 
3; 2 3 5 2+ 12-- 
4, 2 2 2D 4 ime) 2 22 
88, 2 3 3 ice) we og 
WAN D 3 6 10 14 Dy 
135) 2 3) 7 9 I 22 
155; 2 nt I 2 I es Ta 2208 
179, 2 I I 8 II si as 23 
Cagle BD I 3 
279, 2 3 : 
287, 2 3 I 4 9 3 22 
314, 2 4 ee 8 2 24 
B5355 2 2 17) oe is 21 
MAXILLARY. PREMAXILLARY. 
No. Small. Medium. Large. Small. Total.* Small, Large. Small. Total. 
108 a 2% 5 ae 7+ By 2 a 2 
2; 4 ae 5 22 31 8; 2 sy 2 
3, 4 ale 5 23 32 At 2 aS 2 
4; 4 5 a7. 36 o 2 - 2 
88, , =A) Bon, Bey I I 2 
132; I 5 20) 26 Sa My 
155; wd I 5 ge 6+ : 2 2 4 
179; 5 Dee Oe 835 os 2 2 
266, 2 ; 6 19+ 27+ I om 3 
275, a ‘ 5 25+ 32+ oe oy bes a 
270; 2 . 4 italy 27 os 3 Ar 3 
287, 3 7 Syd Mean ey hy 
301, 5 \ 3 15 23 ar te a ie 
3535 3 wa 4 227 “207 5 2 me 2 
From the above table it will be seen that in no instance do the 
size and arrangement of the teeth exactly agree with either 
X. molossus or X. thaumas. The number of teeth is also as varied 
as the size and arfangement, thus: in No. 88, the number of max- 
illary teeth corresponds with X. mo/ossus but the mandible contains 
