and plenty that we have need to remind ourselves constantly that there were no trade routes kept open, no policing of the seas, no international treaties nor diplomatic relations to prevent a peaceful merchant ship from disappearing altogether on the high seas, or staggering into port with the loss of her cargo and most of her crew. The Egyptian stern still survives in these mosaics with modifications, but the greatest difficulty the naval architects appear to have had was with the bow. What to do with the ram-like entrance has obviously been a source of great worry. In the end, so that the merchant ship might not look too war-like, a curve has been added above the bulwarks at the bows to balance the curve at the waterline of the ram. The rowing arrangements exhibit a square hole in the gunwale for the oar to pass through. Of the sailing boats and ships depicted in mosaic the _corbita_ shows a freer design than the others. She is more or less crescent-shaped and not unlike the earlier caravels in hull. A ship of burthen, she has a mast, and the steering oar is seen at the starboard. Another illustration of this type of “corvette” is shown with a steering oar at each side, the sail furled to the yard, a couple of braces and the mast supported by six shrouds—three forward and three aft. The mast has a great rake forward, and there appears to be a narrow platform running round the hull as a side-walk, a relic, no doubt, of the flying deck that kept the marines separate from the rowers. Another sailing ship called the _catascopiscus_ obviously derived her name from the corresponding Greek word meaning to reconnoitre or scout; for she was famous as a light, fast-sailing ship. Her mast and sail are shown in the mosaic, as well as the halyards and the brailing lines. The _actuaria_ was a light, easily propelled ship, similar to the last. The mosaic (reproduced in Fig. 24) shows the sail furled to the yard and, what is significant, a rope-ladder, up which one of the sailors is ascending. Of the other two men one is sculling with two oars, while the captain is seen in the bows holding a mallet, which he knocks on the boat that the sculler may keep correct time and rhythm in a manner not very far separated from the exhortations of the “cox” of our University eights. This was the kind of ship which Cæsar employed during an expedition to Brittany, and will be referred to again in the next chapter. [Illustration: FIG. 24. NAVIS ACTUARIA. _From a mosaic at Althiburus, near Tunis._]