NO. 3 CAMBRIAN TRILOBITES 1 79 



ACROCEPHALITES ? GLOMERATUS, new species 

 Plate 26, figs. 7, Ta 



This species, like A. ? majus (pi. 26, fig. i), is represented by a 

 cranidium that except for the boss on the frontal limb in front of 

 the glabella would be referred to Ptychoparia. As in the case of 

 Acrocephalites haynesi (pi. 24, figs. 4, 4a), there are associated 

 cranidia that are similar to the one with the boss on the frontal limb 

 except that they do not have the boss. The cranidia are preserved 

 in a coarse ferruginous sandstone, and nothing remains of the test 

 or its outer surface. 



In view of the above statement the species is tentatively referred 

 to Acrocephalites. The largest cranidium in the collection has a 

 length of 20 mm. 



Formation and locality. — Upper Cambrian: (340c) Dark reddish 

 brown sandstone, Rawlins, Carbon County, Wyoming. 



ACROCEPHALITES HAYNESI, new species 



Plate 24, figs. 4, 4a-b 



This species is distinguished by strongly defined glabella, fixed 

 cheeks, palpebral lobes, and frontal rim of the cranidium; also by 

 the variability of the length of the frontal limb and the size of the 

 boss in front of the glabella, accompanied by a coarsely granulated 

 outer surface. It differs also in having a strong occipital spine. 



The larger cranidia average 8 mm. in length. 



This species is named after Mr. W. P. Haynes, who collected all 

 the specimens known of it. 



Formation and locality. — Upper Cambrian : Meagher limestone ; 

 on Pole Creek, a tributary of Cherry Creek, about 4 miles (6.4 km.) 

 east of Madison River, Madison County, Montana. 



Type in Museum of Comparative Zoology, Cambridge, Massa- 

 chusetts. 



ACROCEPHALITES INSIGNIS, new species 



Plate 25, figs. I, \a-b 

 All of the numerous specimens bf this species were flattened and 

 more or less macerated in the mud now forming the argillaceous 

 shale in which they occur. The species is characterized by the 

 narrow fixed cheeks, strong palpebral lobes, and the ridges into 

 which they merge on the fixed cheeks. The width of the frontal limb 

 and the size of its median boss are variable, but not as much so 

 as in A. haynesi (pi. 24, figs. 4, 4a). There is no trace of an 



