230 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 64 



DESCRIPTION OF PLATE 24 



PAGE 



Acrocephalites stenometopus (Angelin) 181 



Figs, i, la. (X3-) Reproduction of photograph of the type specimen 

 of the cranidium. 

 i^- (X3-) Matrix of free cheek assigned to the cranidium. 



The specimens illustrated are from the (30911) Agnostus Iccvi- 

 gatus zone of the Middle Cambrian limestone at Gudhem, Skara- 

 borg (Vestergotland), Sweden. Type in Geol. Min. Inst., Lund, 

 Sweden. Plastotype, V. S. National Museum, Catalogue Nos. 

 61555 and 61556. 



Acrocephalites americanus Walcott 177 



Fig. 2. (X2.5.) Dorsal view of a nearly entire cranidium, with the 

 outline of the missing parts restored from other specimens. 

 U. S. National Museum, Catalogue No. 61557. 



2a. (X3-) A cranidium varying in details from fig. 2. U. S. 

 National Museum, Catalogue No. 61558. 



2b. (X8.) Surface of the cranidium of fig. 2 on left side of 

 fixed cheek in front of ocular ridge. 

 3- (Xi-5.) An imperfect dorsal shield with 29 thoracic seg- 

 ments. This is the only specimen known to me that 

 indicates the appearance of the thorax. (Locality gox.) 

 U. S. National Museum, Catalogue No. 61559. 



^a. (X4.) Cranidium and portion of thorax of a specimen from 

 the shale in which the siliceous nodule specimens repre- 

 sented by figs. 2, 2a-c, and 3 were embedded. (Locality 

 112.) U. S. National Museum, Catalogue No. 61560. 



3b. (X 5J Side view of a free cheek associated with this species. 

 (Locality i6d.) U. S. National Museum, Catalogue No. 

 61 561. 



The specimens represented by figs. 2, 2a-b are from the siliceous 

 nodules of locality 89X. These occur in the Conasauga shales of 

 the Middle Cambrian, Coosa Valley, Livingston, Floyd County, 

 Georgia. 



Figs. 3, 3a-b are of specimens from the shale in which the nodules 

 occur, (gox, 112, and i6d) Coosa Valley, Cherokee County, Ala- 

 bama. 



Acrocephalites haynesi Walcott 179 



Figs. 4, 40. (X 3-) Dorsal view and side outline of a small cranidium 

 on which the tubercle in front of the glabella is only 

 slightly developed. 

 4^- (X3-) Dorsal view of two cranidia illustrating variation in 

 frontal tubercle. 



The specimens illustrated by figs. 4, 4a, and 4b are from the Upper 

 Cambrian, Meagher limestone on Pole Creek, Montana. The type 

 specimen is at the Museum of Comparative Zoology, Cambridge, 

 Massachusetts. 



Plastotypes, U. S. National Museum, Catalogue No. 61562, 61563. 



