306 DR. A. GUNTHER ON REPTILES AND FISHES [June 28, 
it; in other parts the common sort is from a Tephrosia, while the 
muddy creeks of the coast are poisoned by the climbing stems of 
Derris uliginosa (Benth.). Fish-poisons do not act equally on all 
species ; and occasionally some of the smaller will continue active 
and unaffected, long after many much larger ones have become in- 
sensible and either forced themselves on shore or floated on the sur- 
face. In the case of the poison from the Derris, this was noticed to 
be the case with the Tetrodon, which remained with a few others, 
not one of which came up, while the other inhabitants of the creek 
were dead. 
“A table is here added, showing the mean temperature, during the 
year, of the African rivers: that of the lake, from the few observa- 
tions made, seemed to differ but little from those of the rivers. 
The temperature of the rivers varies during the day from 2° to 3°, 
according to the amount of sunshine and the mass of water acted 
upon. ‘This has reference to the water in the deep channel: where 
the river becomes much expanded, as over shallow banks, the tem- 
perature is much raised ; but in the deep parts no temperature higher 
than 90° has been observed. 
January. 
February. 
May 
June. 
July 
August. 
September 
October. 
November. 
December 
° ° ° ° ° ° ° ° ° ° ° ° 
82°5 |84°6 |83°5 |78°5 |75°5 |72°0 |70°3 |71°8 |76°0 |80°9 |82°0 |84°6 
“Of Snakes there are many kinds, in size varying from that of 
the Python to the small grass-snakes. A few species are extremely 
venomous, and cases are well authenticated of the same individual 
killing several large animals in succession. Yet the danger to the 
traveller is almost none: during five years spent in company with 
natives, exposed while passing through every sort of vegetation, no 
snake ever offered to bite me, and I have never seen another person 
bitten. Yet our party often numbered thirty, and often slept on 
the open ground exposed at night. Accidents do occur, but are ex- 
tremely rare. 
‘Finally, I must add that this collection has been formed in a de- 
sultory manner, under circumstances not always the most favourable, 
and that it contains many imperfect specimens, which may prove 
difficult of determination.” 
List of the Species. 
Those marked with an asterisk (*) are new. Descriptions of those 
which have not been described elsewhere will form the last part of 
the paper. 
TORTOISES. 
Sternothyrus subniger, Lacép. 
