54 JOURNAIv OF THE 



The specimens I have used are those collected by 

 Professor Kmmons and Professor Holmes, referred to 

 above. 



The rock mass in which the specimens occur is g-ran- 

 ular quartz of a dark color and splits rouo-hly along- 

 apparent planes of bedding-. The weathered surface 

 of the rock is very rough, consisting- of the protruding- 

 fossil-like forms and cavities out of which they have 

 weathered, interspersed with more or less even patches 

 of weathering- concretions. 



These protruding- forms are ccmiposed of quartz of a 

 lig-ht g'ray color, sometimes brown from oxides of iron. 

 Around each of these forms there is a ring- of softer 

 g-rayish white material, which in many cases has 

 weathered below the g-eneral surface of the rock, leav- 

 ing- the forms standing' up apparentl}^ in little cups. 

 The concretions in weathering- are also g^rayish white 

 and are circular in section, showing- concentric struct- 

 ure about very small neuclei. The fossil-like forms of 

 the palaeotrochis are larg-er than the concretions. I 

 counted in an averag-e specimen, twenty of the palaeo- 

 trochis exposed in an area of nine square inches, v.^hich 

 averag-ed about three-eig'hts of an inch in diameter, 

 never varying- much from that size. The concretions 

 were somewhat more numerous and considerably 

 smaller. The palaeotrochis is not distributed evenly 

 throug-h the rock nor does it occur in definite planes of 

 stratification. The individuals are turned in no definite 

 position with respect to each other, but with very 

 rare exceptions one apex or the other of the double cones 

 rests on bedding- planes or on planes parallel to these — 

 not with the axis perpendicular to the plane but inclined 

 at a varying-ang-le depending- upon the flatness of 

 the form. Inother words, their g-eneral position is 



