388 SURG. J. C. THOMPSON ON THE 
The heart is situated 27°6 per cent. down the vertebral column ; 
this is a little further to the rear than is usual in a Colubrine 
snake. The liver is much attenuated both anteriorly and pos- 
teriorly. The parietal plewra is very dark, the parietal peritoneum 
is almost black, and the visceral coverings are unpigmented. 
The vertebral artery rises from the right aortic arch at the 
54th g., courses superficially to the 44th g., and enters in the 
median line. There are four intercostal branches: I-53; 
I1.—52; I11.-50; IV.-47. The right aorta has one large inter- 
costal branch, 1.60, which enters to the left of the median line. 
The dorsal aorta begins at the 62nd g. The intercostal arteries 
enter the left side at the following gastrostege levels: 1-70; 
172 wif > VV 3 Vee Vil=84 Vv M85 Ve oie 
TX.-89 ; X.-92; XI.-95; the branches beyond are injured. 
The external landmarks of the principal viscera in terms of 
gastrosteges are as follows :— 
Gasbrosbe Ses Ui eann.c saan ee 221 100 per cent. 
IRIGENED EY NEG od sunoossGsconoacepaese 61 27°6 
Tei Ver MitO ye eae crmaru tan: 66 29°8 
aE Mea Vee ea Be UTR ae ani 109 49-5 
Gall-bladder ..... Dersatte eG 134 60-4 
TRESS, TBIEAN TINO! a spcossrocasee 160 (ARS 
Ke neha PCI ask Aaa eae 167 75:8 
Ne Netti bi wane es eee oe 172 77°8 
as MEERCTNG pce ena nae aye nee 179 81-0 
Keine ye avelity sblp ees seer errr: 184 84:2 
ss remainder injured. 
The number of scale-rows, the sequence in which they are 
suppressed, and the gastrostege level at which they terminate 1s 
as follows :— 
Neck. 
21 rows, IV row ends, right 7th, left 6th gastrostege, leaving : 
Body. 
19 rows, IV row ends, right 129th, left 128th gastrostege, leaving : 
Vite LEX peo eels 5 Weal a 
ANS yan gi eA Al GLa er as 5 albiist ee a lost 4s 
13 ,, which are continued to the vent. 
The bodies of most serpents taper posteriorly and this is 
usually associated with the loss of definite scale-rows. The rows 
that are suppressed are prone to be either on the middle of the 
flanks or one or two rows distant from the median. When the 
rows on the flanks are dropped the levels at which they terminate 
are usually bilaterally asymmetrical, there being a difference of 
from one to four gastrosteges. When the rows adjoining the 
median are suppressed, the rule is for them to terminate at the 
same level. ‘he pioneer work in this field has been done by 
A. G. Ruthven, Esq. Since the days of Cope, no American 
worker has given so astute a suggestion to students of herpetology 
as is contained in his memoir on the genus Zhamnophis. 
9 
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