394 SURG. J. C. THOMPSON ON THE 
that the intromittent organ is highly differentiated. To this 
may now be added the character to be found in the system of 
air-chambers opening into the trachea. These structural con- 
ditions will justify the removing of this serpent from the genus 
Coluber and reinstating the genus Gonyosoma of Wagler. 
PHILOTHAMNUS SEMIVARIEGATUS Smith, 
Specimen.—Brit. Mus. Nat. Hist. Ex. No. ’13-6. Blue Nile, 
Soudan. Adult female. 
The trachea is black and terminates at the 51st g. The mem- 
brane is well developed and lies along the right side of the tube: 
the air-cells begin at the 45th g. The right bronchus persists as 
an intrapulmonary streak to the 57th g. The right lung is lined 
with air-cells to the 68th g., where they end very abruptly. The 
left lung is a small air-sac opening into the trachea at the 5lst g. 
The external landmarks of the principal viscera in terms of 
gastrosteges are as follows :— 
FASUROSUCCES: Sipe puree ae reece nee 204 100 per cent. 
ear bay ens.ce-tans ec eee eas 51 25 
VET RUN) woe secs e eee cee 65 31:8 
sh Wy OidG Neem acre oe a state 98 48 
Gallbladder ete .cc-n-c eee oe: 114 55°8 
Kaidineysnie bite tips sarees se: 184 90 
ay 3 end!) Raeaee es 198 97 
a2 Nehte taoae ner oseeince ce 187 91-5 
ss Os ENGR cer ota eae 200 98 : 
The scale-rows, the sequence in which they are suppressed, and 
the gastrostege level at which they terminate are as follows :— 
Neck. 
17 rows, IV row ends, right 4th, left 4th gastrostege, leaving : 
Body. 
15 rows, VI row ends, right 112th, left 110th gastrostege, leaving: 
Spee LV Gn ct cee pre UMN yy itl - oh 
11 ,, which are continued to the vent. 
CERBERUS RHYNCHOPS Schneider. 
The salient characters of this species are: All the teeth, 
without exception, are grooved. The tracheal membrane is 
lined with a peculiar type of deep air-cells. The shifting of the 
heart to the rear. The reduction of the renal arteries to one on 
one side and two on the other. The particularly tough con- 
nective tissue, which in this respect resembles that found in an 
Hydrophid and differs from the texture in a Colubrine. 
Specimen:—California Acad. Sci. No. 15301. Cavite Viejo, 
Luzon, Philippine Islands. Cranium. 
There are 16 mawillary teeth which are grooved on the external 
quadrant; separated from these by a small space are two slightly 
enlarged teeth, in a special compartment of mucous membrane, 
