ARSINA´RIUM, PR. (Ἀρσινάριον ἄκρον), aheadland on the W. coast of Libya Interior, placed by Ptolemy (Ptol. 4.6.6) in 8° long., and 12° N. lat., between the two great rivers Daradus ( Senegal) and Stacheir ( Gamnbia); a position exactly answering to that of C. Verde, the westernmost point of the whole continent of Africa. It is true that Ptolemy gives points on the W. coast of Africa more to the W., his westernmost point being the Pr. Cotes, at the mouth of the Straits, which he places in long. 6° [AMPELUSIA]; for he mistook the whole shape of this coast, especially in its N. portion. But still his Pr. Arsinarium is the westernmost point of the coast for a long distance on both sides of it. The geographers who place this cape N. of C. Blancohave not given Ptolemy sufficient credit for the accuracy of his longitudes.
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