THE PRODROMUS 255 



from this source that most beautiful kind of marble which is 

 called Nephirii has its origin, which is nothing else than a 

 deposit of the sea filled with shells of every description, in 

 which a stony substance takes the place of the decomposed 

 substance of the shells. 



The limitation of my plan does not allow me to give an ex- 

 position of all the things which I have remarked worthy of 

 notice in the different kinds of shells dug from the earth; 

 wherefore, passing by other matters, I shall mention here only 

 the following : 



1. A pearl-bearing mussel, found in Tuscany, in which the 

 pearl was clinging to the shell itself. 



2. A part of an unusually large pinna in which, after the de- 

 composition of the byssus, the color of the byssus remained in 

 the earthy matter which had filled the shell. 



3. There are shells of oysters of marvellous size in which 

 are found several oblong cavities eaten out by worms, quite 



^ The term Nephiri is unintelligible. Neither nepheline nor nephrite, to which the word 

 bears closest resemblance, fulfils the requirements of a marine deposit. Maar's note (f ;« 

 Paste Legejner, p. 105) leaves the difficulty unsolved: " Vi har intetsteds kunnet finde nogen 

 Oplysning om TVif^.^zrz'. Professor Heiberg, til hvem vi har henvendt os, antager det for en 

 Trykfejl for nephriti og forraoder, at marmor nephrites er det, der nu hedder Breccia (Mar- 

 markonglomerat) . Hertil maa dog bemaerkes, at nefritisk Marmor naeppe indeholder noget, 

 der af Steno kunde antages for Muslingeforsteninger. Tozzetti {Reisen I, p. 127) omtaler 

 nefritisk Marmor fra Bygninger i Pisa, og angiver, at det i Virkeligheden er en Slags Ser- 

 pentine." See also Opera Philosophica, Vol. II, p. 340. 



It is more probable that Steno wrote Septariutn, which was converted to IVephiri by a 

 printer's error. The change is not difficult to account for palaeographically. The final urn 

 following a vowel was usually indicated by ~ ; .S" was taken for TV ; ph was an error for pi, 

 and /for a. Steno's chirography was none too clear, as may be seen from the facsimile letter 

 inserted by Wichfeld, Erindringer ont den Danske Videnskabsmand Niels Stensen, Dansk 

 historisk Tidsskrift, 3 Raekke, 4, opposite p. 108. That the error was not corrected in the 

 legenda, p. 79, of the original edition cannot be urged against this conjecture, inasmuch as 

 many mistakes in the text escaped notice. 



Septaria are thus described by Chamberlain and Salisbury {A College Text-book of Geology, 

 New York, 1909, p. 48) : "Concretions sometimes develop cracks within themselves, and 

 these may then be filled with mineral matter differing in composition or color from that of 

 the original concretions (Fig. 28). Concretions the cracks of which have been filled by 

 deposition from solution, are called septaria. They are especially abundant in some of the 

 Cretaceous shales and clays. In not a few cases the filling of the cracks appears to have 

 wedged segments of the original concretion farther and farther apart, until the outer surface 

 of the septarium is made up more largely of vein-matter than of the original concretion. The 

 development of concretions in rock is not commonly looked upon as metamorphism, but it is 

 really a metamorphic change in the broadest sense of that term." 



