no. 1833. ORIGIN OF MOLDAVITES— MERRILL. 483 



Suess has suggested should all be included under the name of "tek- 

 tites"), are found, their most striking characteristic is the peculiar 

 markings, which, in the case of those of the island of Billiton, it would 

 seem well-nigh impossible to explain in the present condition of our 

 knowledge. Suess, to whose monograph I am indebted for the most 

 detailed and comprehensive of recorded observations, regards the 

 markings, or sculpturings, and those of "tektites" in general, as 

 undoubtedly a consequence of their mode of origin, and as furnishing 

 conclusive evidence of their ultra-terrestrial source. To this con- 

 clusion the present writer, as will be observed, takes decided exception, 

 and has sought rather to explain them by comparing them with 

 markings on pebbles of various kinds, concerning the origin of which 

 there is no question. 



(1) Obsidian pehbles from near Cali, Department of Cauca, Colombia, 

 South America. — These were received at the Museum from a Mr. B. S. 

 Hobbs through Dr. George F. Kunz, with the simple labeling " Obsid- 

 ian" 1 from the locality above given. Nothing is known regarding 

 their occurrence, nor have I been able to get in communication with 

 Mr. Hobbs with a view of acquiring further data. 



As shown in the illustrations (pi. 62, figs. 1-2) of two of the larger 

 forms, the specimens are roughly spherical, each showing on one side 

 a flattened area as though it had at some time been attached to a larger 

 mass or had remained in one position during the etching process, 

 since the larger grooves are entirely absent from these portions. The 

 surface markings are of three kinds: First, those which appear like 

 original conchoidal fractures, the sharp angles of which have been 

 reduced by corrosion; second, a series of shallow pits and grooves 

 which are distributed fairly uniformly over the entire surface except 

 the fattened portion mentioned; and, third, a very fine stipple-like 

 pitting which gives the surface a shagreen-like appearence. This 

 shagreen effect with numerous small, nearly circular, shallow pits 

 occurs also on the flat areas where the larger groovings are lacking as 

 already stated. The colors are dull black, but by transmitted light 

 smoky brown. These two larger forms are roughly 20 and 30 mm. 

 in diameter, and weigh 12 and 30 grams, respectively. Thin sections 

 under the microscope show a faint smoky glass almost completely 

 isotropic, but with an occasional minute, colorless, doubly refracting 

 point too small for satisfactory determination. A peculiar series of 

 anastomizing cracks much resembling the crackle structure on certain 

 porcelain glazes, traverses the section in all directions. 



The composition of this glass, as shown by an analysis of a portion 

 cut from the larger of the specimens, is given in column I below. In 



» Since the above was written, but before this paper was sent to press, I received from Dr. J. Woldrich, of 

 Prag, a copy of his Beitrag zur Losung der Tektitfrage, in which this and the Arizona samples are referred to. 

 It will be observed that I still hold the opinion expressed in my letter to Doctor Woldrich and by him 

 quoted. 



