NECTURUS MACULATUS. 391 
vertebrae at the sacrum, and but three at the first haemal arch. The results of counting 
the vertebrae in 100 specimens are expressed by Bumpus in the following table :— 
No. of vertebrae. No. of specimens. 
45 : : : : 2 
44 § : : 9 
45 : ; : ; : 21 
46 ; : : : : 18 
47 14 
48 16 
49 11 
50 5 
51 : 4 
100 
By this it will be seen that the average total number is 45 or 46. 
A Typical Vertebra. 
In order to understand the structure of the separate vertebrae, any trunk vertebra 
except one of the first two or three may be selected as a type and its parts studied in 
detail, after which the differences seen in other regions may be noted, and a few special 
vertebrae selected as worthy of individual study. The 16th vertebra has been selected 
for this purpose, and four views are given of it in text figures 1-4. These figures were 
drawn from a dried vertebra prepared by macer- 
Centram, wit 
TAA, ArT. Concavily Sus 
aN : ie ant. Zy9@ Pophy 
y oi) b loirh Qytic. Facet. 
y 
y) wf 
Re 
Wie? 
ation in caustic potash and hence lack the cartilag- 
inous portions and other related soft parts referred 
to in the text. 
This vertebra consists primarily of a ventrally 
: M2 > 
situated centrum or body; a neural arch, the dorsal le) 2 So 
“hi ; Ne) 2 NBN 
aspect of which is broadened out into a broad, flat i" 2 EH, eee 
c a Yi 8 P/F blewrape bhy- 
plate; and upon each side a complicated transverse a Siat carblage 
\ ophysis. 
\ Diapophy 
process directed backwards and bearing a short rib 
which articulates with it in two places. 
Socket for cartilagi- 
of Neéurapophysis 
The centrum is in the form of a slender hour 
ye 
median process. evs tip 
o = 71 Cr ale aS ea a = 
glass, its ends marked by iS) deep ne shaped Fig. 1. 16th vertebra; dorsal aspect. X 3. 
depressions, thus making the entire vertebra con- 
