Dr. H. Woodward — M. Cambrian Fossils of the MocJcies. 537 



but in two specimens one had 14 segments and one 15 thoracic 

 segments. Of eleven specimens in the Whyraper Collection three 

 had 12 segments, four had 13, one had 14, one had 15 ; and two 

 had 18 thoracic segments. I think the number of segments must 

 therefore be considered inconstant, or that an examination of a larger 

 number of specimens may prove the existence of a second species 

 broader and shorter than Ftychoparia Cordillerce. 



The glabella is tumid, but rather narrower and rounded in front, 

 wi(h three marginal furrows ; the fixed cheeks surround it in front, 

 the border being bent upwards and forming a strong raised rim ; 

 fix«d cheeks are very broad in front ; eye-lobe short, distant from 

 the glabella, but united to it by a well-marked ocular ridge ; free 

 cheeks narrow, with bluntly pointed lateral spines which extend 

 backwards only to the second free thoracic segment ; axis equal 

 to ♦ne-third the breadth of body-segments in front, but tapering 

 gradually from 4 mm. at the neck-furrow to 1 mm. at the pygidium ; 

 pleirse parallel, but little curved, fulcral groove deep, margins of 

 pletraa raised ; pygidium very small, consisting of three coalesced 

 segments; the axis extends nearly to the extremity; two pairs of 

 lateial furrows faintly mark the pleurse in the shield. 



I have not been able to detect the granulated ornamentation 

 observed by Dr. Matthew in this Trilobite, nor the row of low 

 tubetcles on the median line of the thorax. Whether the ornament 

 can le seen or not depends so much upon the fineness or roughness 

 of thj matrix in which these small fossils are preserved. 



Dx Matthew observes that among the Trilobites of the fauna of 

 Mount Stephen Ftychoparia is the only one which has a specially 

 Low^ Cambrian aspect. The genus is now a very extensive one, 

 and las absorbed a great number of species formerly referred to 

 Cono^pJialites, but certainly the whole of the latter genus does not 

 belong to Ftychoparia. 



Zacanthoides (Olenoides) spinosus, Walcott, 1886. 



OlenoiL spinosus, "Walcott, 1886: Bull. U.S. Geol. Surv., No. 30, p. 184, pi. xsv, 



figs. 6, 6a. 

 Emboliius, Westwood, 1883 : Pliil. Mag., ii; a genus of Hymenoptera. 

 {Embolintis) spinosa, Romiuger, 1887: Proc. Acad. Nat. Sci. Philad., p. 15, pi. i, 



fig. 3. 

 Zacanthides spinosus, Walcott, G. F. Matthew, 1899 : Proc. & Trans. Roy. Soc. 



Canada [2], vol. v, p. 57. 

 Zacanthides spinosus, Walcott, 1888 : Amer. Joui'n. Sci. [3], vol. xxxvi, pp. 164-5. 



Onlyone poorly preserved example (impression and counterpart) 

 of this interesting form has been brought home by Mr. Whymper ; 

 but by he great kindness of Drs. Whiteaves and Ami I have been 

 allowed to see four excellent specimens, one with a fine head, 

 selectedfrom the collection of the Geological Survey of Canada, in 

 Ottawa, made by Dr. Ami and others from Mount Stephen. 



The specimen is 55 mm. long and 35 mm. broad across the head; 

 length (f head, 17 mm. ; length of thorax, 23 mm. ; length of 

 pygidium 15 mm. 



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