NO, 22 CAMBRIAN TRILOBITES, 3D CONTRIBUTION RESSER 1 7 



Unfortunately, the lectotype is an imperfect specimen, for which 

 reason reference of the specimens subsequently described from Wash- 

 ington County to the species must remain somewhat doubtful, l^he 

 pygidia illustrated in 1891 show two species, but whether the differ- 

 ence is merely one of drawing cannot now be determined, since one 

 specimen cannot be found. 



Lower Cambrian, Schodack; (loc. 27) Troy, and (loc. 38c) i mile 

 north of Middle Granville, New York. 



Lectotype and plesiotypes. — U.S.N.M. nos. 15425, 1745 1. 



Kootenia troyensis, n. sp. 



Solenopleura .' nana Walcott (part), loth Ann. Rep. U. S. Geol. Surv., 

 p. 658, pi. 98, figs. la, 2, 1891 (see K. nana). 



The illustrations, poor as they are, show the specific difference of 

 this species in size, contour, and width. It may have scattered granules 

 on the test. 



Occurrence same as preceding. 



Holofype. — U.S.N.M. no. 94342. 



Kootenia masoni, new name 



Dorypygc quadriceps Mason (not Hall and Whitfield), Bull. Southern Cali- 

 fornia Acad. Sci., vol. 34, pt. 2, p. 116, pi. 15, figs. 18, 20-22, 19?, 1935. 



This species differs considerably from K. quadriceps. The head is 

 shorter, and the pygidium is more completely fused. It is the shortness 

 of the pygidial spines which serves to separate K. masoni most easily. 



Middle Cambrian, Cadiz; Marble Mountains, California. 



Cotypes. — Los Angeles Mus., nos. A-2471-18 to 22. 



LITOCEPHALUS, n. gen. 



Diagnosis. — Cranidium quadrate or rectangular in outline. Glabella 

 clearly defined, tapered, and truncated in front. Glabellar furrows 

 absent, or a rear pair very faintly indicated. Suture moderately 

 divergent anterior to the eyes. Brim wide. Rim clearly marked, flat 

 but slightly swollen, and more or less upturned. Preglabellar area 

 convex, wide, more than twice width of rim. Eyes of moderate size 

 situated about the middle of the glabella. Fixigenes two-thirds the 

 width of the glabella at the palpebral lobe. Eye lines of moderate 

 development. Test mainly smooth but with other parts unknown. 



LitocepMus is similar to Wilbernia, only two essential differences 

 being apparent. In the first place, Litocephalns is much wider, but too 

 few of the species on hand have been studied to ascertain whether this 

 is a generic difference or only merely the results of comparing two 



