NO. 5 - CAMBRIAN TRILOBITES 377 



OGYGOPSIS KLOTZI (Rominger) 

 Plate 66, figs, i, la-b 



Ogygia klotzi Rominger, 1887, Proc. Acad. Nat. Sci., Phil., p. 12, pi. i, fig. i. 



(Describes and illustrates species.) 

 Ogygia ? klotci Walcott, 1888, American Jour. Sci., 3d ser., Vol. 36, p. 166. 



(Notes difiference between this species and typical forms of Ogygia.) 

 Ogygopsis klotzi Walcott, 1889, Proc. U. S. Nat. Mus., Vol. 11, p. 446. 



(Proposes Ogygopsis with Ogygia klot.ci as the genotype.) 

 Ogygia (Ogygopsis) klotzi Matthew, 1899, Trans. Royal Soc. Canada, 2d 



ser.. Vol. S, Sec. 4, p. 58. (Describes species and supposed young of 



same.) 

 Ogygopsis klotzi Woodward, 1902, Geol. Mag., Dec. 4, Vol. 9, p. 530, text fig. i. 



(Describes and discusses species and its relations to other genera. Gives 



outline figure.) 

 Ogygopsis klotzi Walcott, 1908, Canadian Alpine Jour., Vol. i. No. 2, pi. 4, 



fig. 4. (Illustrates entire dorsal shield.) 

 Ogygopsis klotzi Grabau and Shimer, 1910, North American Index Fos., 



Vol. 2, p. 289, fig. 1597. (Description and reproduction of Walcott's 



figure of 1908.) 



The characters of this species have been given in the description 

 of the genus Ogygopsis. There is no closely related Cambrian species 

 with which it may be compared. Orria elegans of the Middle Cam- 

 brian has a somewhat similar pygidium, but the differences in the 

 thoracic pleural furrows, fixed cheeks, and palpebral lobes are of 

 generic value. 



The nearest Ordovician form appears to be Ogygiocaris bitcliii 

 (Brongniart),' from which it differs in its glabella, palpebral lobes, 

 presence of palpebral (ocular) ridge on tixed cheeks, and axial lobe 

 of thorax and pygidium. 



Ogygopsis klotzi is the most abundant fossil at the Mount Stephen 

 locality, and hundreds of specimens of the dorsal shield without the 

 free cheeks have been collected. The vertical range of the species 

 in the Stephen formation is about 200 feet (60 m.). Its vertical range 

 at locality 556 in Utah as far as known is only a few feet. The very 

 limited geographic range of the species in British Columbia is most 

 noticeable, and it is limited so far as known to one other locality in 

 Utah. 



Dimensions. — The largest dorsal shield in the collection has a 

 length of II cm. 



^ Monogr. British Trilobites, Salter, Pal. Soc, 1864-1883, p. 125, pis. 14, 15. 



