1904 M. centrata concentrica

More from the 1904 Hay publication: Malaclemmys centrata concentrica. The Chesapeake Terrapin. Distribution. The littoral region of the eastern United States from Buzzards Bay, Massachusetts, to Virginia or North Carolina; Long Island Sound, Delaware and Chesapeake bays, &c. Characters. The carapace has in general the form of that of M. centrata, but is broader posteriorly and the marginal plates behind the bridge are seldom revolute; the plastron, also, is less convergent posteriorly; the plates of the carapace bear conspicuous concentric ridges, but those of the plastron are smoother, nearly always, however, except in some old individuals, showing at least traces of the lines of growth; the head is small, narrow, and neatly formed, the top of it flat, giving the nose a sharper appearance than is to be seen in the other form of this species. The color varies from uniform black to light brown, the latter always marked with darker concentric lines on each plate of the carapace and more or less blotched with darker on the plastron; the skin of the head, legs, and tail varies from nearly pure black to a very light green-gray, the latter more or less marked with specks and short crooked lines of black; the lips and top of the head are usually dusky, but individuals may be found with either or both white. The males resemble the females in the shape of the carapace, except that they are a little sharper posteriorly and the marginal plates are frequently a little revolute; the nose is much sharper than in the females. It seems very probable that some of the types of coloration indicate local variation, but the species has been so thoroughly mixed by the shipping of large consignments from one place to another that it is doubtful whether anything of this kind could be proved. All the specimens from Connecticut and northern localities, so far as I have seen, are very light in color, with conspicuous concentric markings, but very smooth shells; the Potomac River specimens are similar, but have rougher plates; those from the ocean and inclosed bays of the Atlantic coast of the Maryland-Virginia peninsula are, in more than 75 percent of the specimens, very dark and without markings of any kind. The terrapin from Delaware Bay are more like those of more northern localities, but usually present very little contrast in the color markings on the plates of the carapace. Many varieties are recognized by the dealers in terrapin – “Chesapeakes,” “Delaware Bays,” “Long Island terrapin,” “Connecticuts,” &c. – but in most cases the determinations are nothing more than guesswork.