382 THE AMERICAN NATURALIST. (VoL. XXXIX. 

remains which give a very good general idea of the crab as a 
whole. These larger concretions also have the various parts 
excellently preserved as will be noted in the description. 
Dr. Edward Hitchcock was the first definitely to publish the 
occurrence of the crab remains at Gay Head. He spoke of 
them in his earlier reports on the geology of Massachusetts. In 
the Final Report of 1841, he speaks as follows : — 
“Crustacea. In the green sand at Gay Head we meet with 
well-characterized specimens of the genus Cancer; although they 
are in general much broken, showing that they originally be- 
longed to a formation which was abraded or destroyed anterior 
to the production of the green sand. The interior part of the 
specimen consisted of argillaceous matter, probably containing 
a large proportion of oxide of iron; but the covering of the ani- 
mal still retains its black shining color, although apparently 
carbonaceous. The broken state of nearly all the specimens, 
renders it difficult to determine whether they belonged to more 
than one species, although they probably did: and for the same 
reason I have thought that drawings would not be of use." 
In 1844, Sir Charles Lyell remarks at some length concern- 
ing the structure and fossils of the Gay Head exposure, both in 
the Proceedings of the Geological Society of. London 'and in the 
American Journal of Science. In the latter (vol. 46, 1844, p. 
319) he refers to the crab remains in the following words : — 
“Crustacea. A species considered by Mr. Adam White as 
probably belonging to the genus Cyclograpsus, or the closely 
allied Sesarma of Say, and another decidedly a Gegarcinus." 
In 1863, Dr. William Stimpson described Archeoplax signifera 
from the Gay Head greensand and mentioned that there is an- 
other species although he did not attempt to name it (Boston 
Journ. Nat. Hist., vol. 7, PP. 583-589, pl. 12). 
In 1900 (Proc. Amer. Acad. Arts and Sci., vol. 36, no. I, pp. 
1-9, pls. 1-2), Professor Alpheus S. Packard describes a new 
fossil crab, Cancer Proavitus, from Gay Head and gives a few 
notes and several photographs of Archeoplax signifera Stimp- 
son. 4 
Specimens representing the latter species were especially 
abundant in the material collected during the last two summers. 
