The “British Zoology” included the description of the species of animals at that time known to inhabit Great Britain, except the insects. So good was the work and so accurate were the descriptions, that it was translated into Latin and German, and had a large circulation abroad. Anxious to compare his work with those of foreign naturalists, and to see the specimens of similar animals in the great continental museums, Pennant travelled abroad in 1765, and made the acquaintance of the most important zoologists of the day. He visited Buffon at Montbard, and their friendship led to a correspondence, which lasted for years. Then he went on to Switzerland, and met Haller at Berne. Coming home by way of Germany and Holland, he met a distinguished traveller and naturalist, Pallas by name. Pennant wrote about him: “Our conversation related chiefly to natural history, and as we were both enthusiastic admirers of our great Ray, I proposed his undertaking a history of quadrupeds on the system of our countryman, a little reformed. He assented to my plan, and wrote me a long letter in which he sent me an outline of his design, and his resolution to pursue it with all the expedition consistent with his other engagements.” Pallas went to Russia, and never accomplished his object, but Pennant followed out the idea himself, and in 1771 published a work with the title of “A Synopsis of Quadrupeds,” illustrated with about thirty plates. This was intended as a kind of index to the species of animals described by Buffon in his great work on natural history. He gradually, however, extended its limits, and included in it the description of many animals which he had observed in collections or which had been discovered by travellers, and which had been unknown to Buffon. Years afterwards the great Cuvier said of this work, “that it is still indispensable to those who wish to study the history of quadrupeds.”