NO. 3 CAMBRIAN AND OZARKIAN TRILOBITES 93 



HOLTERIA PROBLEMATICA (Walcott) 



Plate 15, figs. 17-21 



Ogygia ? problematica Walcott, 1884, Monogr. U. S. Geol. Surv., Vol. 8, 

 p. 63, pi. 10, figs. 2a, b, 4. (Original description and illustration.) 



Holteria problematica Walcott, 1924, Smithsonian Misc. Coll., Vol. 75, No. 2, 

 p. 57, pl- 13, fig. 7. 



See original description of the species. 



Formation and locality. — Upper Cambrian: (58) Secret Canyon 

 shale. East side of New York and Secret Canyons, Eureka District, 

 Nevada. 



Genus HOUSIA Walcott 



Ceratopyge Walcott, 1912, Smithsonian Misc. Coll., Vol. 57, No. 7, p. 2^,3. 



Housia Walcott, 1916, Smithsonian Misc. Coll., Vol. 64, No. 5, p. 374. (Sub- 

 genus of Dolichomctopus: type D. (Housia) varro Walcott.) 



Sodalitia Walcott, 1923, Smithsonian Misc. Coll., Vol. 67, No. 8, p. 471. 

 (In lists.) 



Housia Walcott, 1924, Smithsonian Misc. Coll., Vol. 75, No. 2, p. 57. 



Description. — The type species when first described was made a 

 subgenus of Dolichomctopus, the cranidium being incorrectly drawn 

 because a portion of the specimen was obscured in the matrix. The 

 generic name Sodalitia was proposed in lists ' for forms now known 

 to belong to this genus. 



Cranidium long and narrow. Glabella not separated from fixed 

 cheeks. Eyes rather small situated opposite the middle and narrowest 

 part of the cephalon. Postero-lateral limbs long and narrow with a 

 shallow intermarginal furrow. The cranidium slopes down rapidly 

 a short distance in front of the eyes and flattens out again, somewhat, 

 into the frontal rim and border, which is moderately wide. Facial 

 suture intramarginal. A central keel-like fine is faintly visible on 

 most specimens of the glabella and some have a tubercle directly 

 between the eyes and another in the occipital region. Glabellar furrows 

 none or very faint on upper surface. Three sets visible on some casts 

 of the interior. The front set consists merely of two dots and is 

 situated in front of the eyes. The other two sets increase in size, 

 until the third one, beginning at a point opposite the hindermost edge 

 of eyes and extending obliquely backward, attains considerable length. 



Free cheeks with a wide border, with or without a genal spine. 

 Those without a spine become quite circular in outline. A doublure of 

 even width passes entirely around the cephalon and is apparently of 

 one piece. 



^ See Synonymy. 



