Scorpions, centipedes, and poisonous spiders also were not unfrequently brought into the ship with the wood, and occasionally found their way into our beds; but in every instance we were fortunate enough to discover and destroy them before they did any harm. Naval officers on this coast report that, when scorpions and centipedes remain a few weeks after being taken on board in a similar manner, their poison loses nearly all its virulence; but this we did not verify. Snakes sometimes came in with the wood, but oftener floated down the river to us, climbing on board with ease by the chain-cable, and some poisonous ones were caught in the cabin. A green snake lived with us several weeks, concealing himself behind the casing of the deckhouse in the daytime. To be aroused in the dark by five feet of cold green snake gliding over one's face is rather unpleasant, however rapid the movement may be. Myriads of two varieties of cockroaches infested the vessel; they not only ate round the roots of our nails, but even devoured and defiled our food, flannels, and boots. Vain were all our efforts to extirpate these destructive pests; if you kill one, say the sailors, a hundred come down to his funeral! In the work of Commodore Owen it is stated that cockroaches, pounded into a paste, form a powerful carminative; this has not been confirmed, but when monkeys are fed on them they are sure to become lean. On coming to Senna, we found that the Zulus had arrived in force for their annual tribute. These men are under good discipline, and never steal from the people. The tax is claimed on the ground of conquest, the Zulus having formerly completely overcome the Senna people, and chased them on to the islands in the Zambesi. Fifty-four of the Portuguese were slain on the occasion, and, notwithstanding the mud fort, the village has never recovered its former power. Fever was now very prevalent, and most of the Portuguese were down with it.