The mean temperature of Crato is much lower than that of Icó; it is not considered so healthy as the latter place, for the heat of the day is nearly as great, although the nights are much colder. Ophthalmia is truly endemic, and, during some part of the year, few escape its effects: I had an attack which confined me to the house for several days. Many persons suffering from the disease in its chronic state, consulted me, and I gained no little reputation from having either cured or much alleviated the symptoms in most of the cases that presented themselves, even when the complaint had been of long standing; blindness is a very common result, and nowhere have I seen a greater number of blind people than in this district. Secondary syphilitic complaints are also very common, and many are the miserable wretches which they have here produced; in such cases, mercury is very seldom employed for the primary symptoms, these being generally cured by a species of _Croton_, commonly known by the name of Velame; it is used both externally and internally with some effect, but under this treatment sooner or later the secondary symptoms make their appearance, under some one or other of their protean forms. A residence of but a short time in the interior of Brazil, would soon convince those medical men who would cure these complaints without mercury, of the danger of such treatment. CHAPTER VI. CEARA CONTINUED. Reasons for delaying journey into the Interior—Visits, meanwhile, different places in the Vicinity of Crato—Crosses the Serra de Araripe—Reaches Cajazeira—Arrives at Barra do Jardim—Description of that Town and Neighbourhood—Meets with an interesting deposit of Fossil Fishes—Geological character of the Country—Detects a very extensive range of Chalk formation—First discovery of such Beds in South America—The accompanying formation described—This range of Mountains encircles the vast Plain comprising the Provinces of Piauhy and Maranham—Arrives at Maçapé—Great Religious Festival on Christmas Day—Meets with an Accident—Visits also Novo Mundo—Discovers other deposits of Fossil Fishes near these places—Vegetable productions along the Taboleira—Different Tribes of uncivilised Indians in that Neighbourhood—Curious account of the Fanatical Sect of the Sebastianistas—Their extravagant belief—Commit human sacrifices—Their destruction and dispersion—Returns to Crato.