l80 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 64 



occipital spine, but one specimen of the thorax has a median spine 

 on the sixth and seventh segments, and another has a similar spine 

 on the seventh, eighth, and ninth segments. The specimen illus- 

 trated has 21 thoracic segments. The surface is strongly granulated 

 where well preserved. 



Formation and locality. — Middle Cambrian: (112, 112a) Cona- 

 sauga formation shales; about 5 miles (8 km.) east of Center, 

 Cherokee County, Alabama. 



ACROCEPHALITES ? MAJUS, new species 



Plate 26, fig. I 



This species is represented by a single specimen of the cranidium 

 that is flattened in an argillaceous shale. It was referred in my 

 field notes to Ptychoparia, but the presence of the rounded boss on 

 the frontal limb in advance of the glabella and coarse granulations 

 on the outer surface serve to place it nearer Acrocephalites than to 

 Ptychoparia. The granulated surface has been greatly obscured by 

 the pressure to which the test has been subjected. In form the 

 cranidium is similar to that of A. tutus (pi. 24, fig. 6) and com- 

 pressed specimens of A. americanus (pi. 24, fig. ;i)a). A small 

 median node occurs near the posterior margin of the occipital ring. 

 The generic reference will remain doubtful until more and better 

 preserved specimens are found. 



Formation and locality. — Middle Cambrian: (4g) Wolsey shale; 

 5 miles (8 km.) east-northeast of Logan, and i mile (1.6 km.) north 

 of forks of East and West Gallatin Rivers, Gallatin County, Montana. 



ACROCEPHALITES MULTISEGMENTUS, new species 



Plate 24, figs. S, 5a 



This small and very distinct species has narrow pleural lobes, 

 strongly granulated surface, and 25 thoracic segments. The pleural 

 furrows of the thoracic segments are very narrow, short, and rather 

 insignificant when compared with those of A. americanus (pi. 24, 

 fig. 2,0'), and less so with those of A. insignis (pi. 25, fig. la). The 

 frontal border and rim are somewhat similar in form to those of 

 A. f majus except in the upward curvature of the frontal rim and the 

 broader base of the glabella of A. insignis. 



Formation and locality. — Upper Cambrian: (son, 30 o) Weeks 

 formation; 2 miles (3.2 km.) south of Millard Pass, House Range, 

 Utah. 



The horizon of 30 o is 170 feet above that of 3on in the strati- 

 graphic section. 



