CRUSTACEA. 
109 
Length of carapax behind the base of the frontal 
horns nearly 31 inches. 
Genus Epialtus, (Edwards.) 
E. Nuttallii. Mus. Acad. PI. III. 
Testa polita, atropurpurea, maculis testaceis postice sub- 
ocellatis ornata; margine obtusfe tridentata; rostro depresso, 
apice profundi! emarginato: corpore infra sanguineo, ocellis 
testaceis ornato. 
Shell smooth, dark purplish, besprinkled with 
testaceous spots becoming large and somewhat 
ocellate behind, and still larger and brighter on the 
under side of the body ; rostrum broad at base, flat- 
tened above; apex profoundly notched; carapax 
moderately elevated, having three obtuse, distant 
teeth on either margin, including the post-orbitar 
one ; hands in the male very large. 
Length of carapax in the male about four inches, 
inclusive of the rostrum ; greatest breadth, a little 
over three inches. 
A single pair, brought by Mr. Nuttall from Up- 
per California ; the female, but an indifferent spe- 
cimen, is represented on the accompanying plate,* 
because the great size of the male does not admit 
of its beino- figured without reduction. The male 
differs from the female, not only in being twice as 
large, but in its colors, which are brighter, and in 
its spots, which are larger. 
* On the plate the name Libinia Nuttallii has been appended, a mis- 
take which could not be corrected after the impression had been 
struck off. 
