In this "previous note" we are presenting the results obtained by our Researches and referring to the waters of junction around the Island of Casca, located between the Trapandé Bay and the Canal of Ararapira, in the Lagoon Region of Cananéia, in the southern part of the S. Paulo State, Brazil. This note is a continuation of the physical and chemical researches of the Hydrographie System of the Cananéia Lagoon Region. In the Bull. Inst. Paulista de Oceanografia, vol. I, fase. I, pág. 45, 1950, we present the first results of the works carried out in the region. "We give the situation and description of the Island of Casca 's region, situated approximately near the crossing of lat. 25º4' S with long. 48º3'30" W; a bathymétrie study and the results obtained by our preliminary Technical Researches. We referred to the water samples collected from 8-12-48 to 27-10-49, the results of which are shown on table I and II. We discussed all these results, showing some graphics and comparing them with the physical and chemical properties of the surrounding waters - Table II and IIa. We constructed a T-S diagram in order to make evident the particularities which may exist. We discussed the origin of the predominating waters of the Island of Casca's region of junction, having made a tentative essay of dynamics. The previous and undermentioned conclusions will be dully fitted of with the corresponding instruments: 1) As the region under observation has several sand banks the channels leading to Ararapira may suffer or not some modifications; 2) The variation of salinity is of the lagoon type, suffering the influence of tidal currents and the continental contingents; 3) The predominating waters of the region come, first during ebb from the Ararapira channel and second during high tide the superficial layers come in the Bay from the entrance of the region, since the entrance is blocked by the tidal flood, then by the rising of the water level, they enter into the region of junction; 4) The fall of the dissolved oxygen could not be explained, due to the complexity of the interfering factors, and stilJL depends on future studies; 5) The T-S diagram put in evidence the periods of greater or smaller influence of the continental contingents which reach the locality in the months of January, February, March and June, July and August and shows the harmonic variation of the salinity between waters of surface and depth.

In May 1950 a trip was undertaken by the ships "Baependi" and "Vega" to the Trindade Island - 20º30'S and 29º20'W - Approximately 1200 km off the coast of Espirito Santo State. This scientific expedition was realized by the iniciative of the Minister J. A. Lins de Barros. In this expedition the supervisor of the oceanographic works was Prof. W. Besnard, the director of the São Paulo Oceanographic Institute. He brougth home 42 samples of water for study, collected upon the insular terrace of the island, referring to the 15 established stations - see table I - with depths varying between 0 m and 115 m. The physical and chemical properties of them are to be seen on table II. The results obtained were compared with those of the German Expedition to the South Atlantic, 1925/27 ("Meteor"), observed at the stations 157-158-159-163 of profile VI and 168-169-170 of profile VII. The mean results obtaneid by the boats "Baependi" and "Vega" are represented on table IV. We constructed vertical sections - I to VI - of each group of Stations, showing the slope of the insular shelves and, in a general manner, the distribution of salinity. We made also longitudinal section - E, M, I - involving the island and corresponding, respectively, to the groups of stations, the farthest, nearest and intermediary ones. As the number of samples received is reduced and consequently the data obtained are few, no conclusions could be deduced. We made only a commentary supposing that the predominating waters surrounding the island are the same as those coming from the mentioned stations on Profile VI, marked by the "Meteor". No indication authorizes the supposition that waters of the Brazil Current or those of Profile VII of the "Meteor" reach the Trindade Island. On the contrary, its waters must be warm and salted to which Albert Defant (Die Troposphaere, Wiss. Erg. D. Atl. Exp. "Meteor" Band VI, 1 Tel Lief. 3, Berlin, 1936) has referred, as the island is located very near to the limits of the perspective diagram of warm water circulation pointed out. (Kieler Meeresforschungen, Inst. Meereskunde, Universit. Kiel, Band VII, Heft 1, S 24, 1950).

The present elaboration is a "previous note" about two watercourses, Maria Rodrigues and Baguaçú, belonging to Hydrografic System of the Cananeas Lagoon Region in the Southern Part of it he Coast of the Estado de São Paulo, Brazil, which is the objete of our physical and chemical researches. It is based on the first results obtained from our contact with that region, ttfie studies of which are being continued and will still have to confirm or not the previous conclusions, which we are presenting in this "provisional paper". We studied the Maria Rodrigues and the Baguacu under the discussion whether they are to be clasified as a river in the poper sense ot the word or waUer-courses of any other origin. For this purpose we established observatory-stations along their whole course where we collected quantities of water to be analised. The data included in the table nº 1 and 2 refer to the physical and chemical properties of these portions of water. These physical and chemical properties were discussed and compared one with the other according to the observatory-stations, at the same moment and the tide predominating on that occasion. The physical and chemical datas were obtained according to the norms recommended by the Conseil International permanent pour l'Exploration de la Mer, Copenhague. We also presented a sketch of both; we described their relations with regard to the Mar de Cananéia; we inserted comprehensible histograms of the distribution of the observatory-stations, each of them with the respective indices, and at last we tried to correlate the occurrence of the "plancton" with the physical and chemical properties of water as well in the Maria Rodrigues as in the Baguacú. From these researches result the following previous conclusions: 1 - By the data obtained up to now nothing could be formulated as to a cyclical or "seasonal" aspect. 2 - By the comparison of the phenomena which present the rivers in the proper sense of the word and those observed in the Maria Rodrigues and the Baguacú, we are convinced that both are water-courses of the classical type "marigot,". 3 - Their channels are maintained open by the effect of the tide and, more perphaps, by the infiltration-water deriving from the underground-water level owing to the type of the soil of that region, which in mean shows an elevation of 2-4 meters over sea-level. 4 - From tables 1 and 2 and histograms 2 and 3 we stated that the water, not only of the Maria Rodrigues but also of the Baguacú, conserve more or less the same physical and chemical properties, provided that: 1) the localities to be compared are the mouths or equidistant points from them in the lower course, and 2) the moment and tide must be the same. Tables 3a and 3b show sufficiently this supposition.