01. AT HOI.TKUAHL. [SEC. AFCT. KXI'. FKAM 



\Ve ha\ e not a fesv piece- I'M. in the beds mentioned above al < '.ape ( <am- 

 perdown. Various sandstone-, are in e\ idenre. red and grey, line grained 

 and coarse mained. Sonic plainly exhibit ripple marks mi the upper 

 surface. A microscopic -ection id' a line Drained sandstone sho\\- 

 -omewliat rounded i;ram> of less than 0.5 in. in. in si/.e. almost entirely 

 counting of quart/, with hnl a few grains of felspar. A rock of coarser 

 -rain, showing grain> a> large as several in. m.s. contains much more 

 felspar, especially microcline. (See pi. 4. (ig. !M We also find a beautiful 

 piece of lime-conglomerate from the lower portion of the sedimentary 

 series. iSee pi. 4. lig. Hh. This shows pieces up to 1 dm in si/e, of a 

 grey limestone, extremely compact in some parts, lying in a lighter and 

 comparatively coarse crystalline matrix of calcite frequently also with 

 quart/, grains. The pebbles in the main are rather flat or lenticular 

 As regards the flat pebbles the distribution shows an indication of 

 parallelism. 



The limestone in which the fossil remains were found in loose 

 pieces, is a very fine crystalline yellowish-grey rock. 



As regards the fossil remains themselves, they are deplorably frag- 

 mentary. We have some incomplete pieces of a quite small trilobite 

 form: some free cheeks, a very imperfect specimen of the central part 

 of the head shield and one incomplete pygidium. 



The specimens, of which some are represented in pi. 4 fig. 1 3, 

 belong indoubledly to a Ptychoparia sp. but no exact identification 

 can be made with the above material. The specimens show a very 

 dose comformity with certain of the Ptt/rlto/xn-ia forms described by 

 HALL and WIHTKIKI.D as r/v/mv/,/m///,s from the Postdam (iroup in 

 Nevada, in "(ieol. Kxploration of the Kortieth Parallel". In (In- 

 form of both the cheek and of the pygidium the above form lies 

 very near P. ani/tiix (I. c. p. iM), p|. II. lig. 19 21). and also 

 the two forms P. tiUidnx (p. -1\ pi. II. ligs. 8, 10) and /'. tiinmlnlor 

 Ip. 218, pi. II. figs. 16 IS), which WALCOTT in ..The Paleontologv 

 of the Knreka district" p. .".7. combine> into one form. /'. niti(h<x 

 M\I.I and \\'m 1 1 11:1 h. The central portion of the head shield exhibits 

 -onie divialion from that of the forms abo\e mentioned. It has a 

 narrower Irontal limb, and also the facial sutures diverge less markedly. 

 A- re-ards the central portion of the cephalon. this agrees better with 

 Ihnt of /'. lutixtilfdlnx. shown in "(leol. Ivxpl. of the Forth. Par." pi. II, 

 lig. L'i. 



