PETROLISTHES AGASSIZII. 69 
Station 3413. 1360 fathoms. 2 males, 6 fem. 
ce 3429. Gil9\ 2 males. 
a S4ole 995" © 1 male, 2 fem. 
Ee aye, IE 1 male, 1 fem. 
The carcincecia are Gastropod shells which support, and in most cases 
are more or less completely absorbed by, a sea-anemone or a colony of 
Epizoanthus. Among the determinable shells are Solariella, Natica, and Phos. 
Famity PORCELLANID 4. 
PETROLISTHES Stumps. 
Proc. Acad. Nat. Sci. Phila., X. 227, 1858. 
Petrolisthes occidentalis Srimrs. 
Ann. Lye. Nat. Hist. N. Y., VIL. 73, 1859. 
Reef at Panama, March 12. 4 males, 8 fem. ovig. 
In recent alcoholic specimens the transverse ridges and squamiform tuber- 
cles of the carapace are dark red, the intervening spaces yellowish. The 
lower surface, including the abdomen, deep madder. 
Petrolisthes agassizii Fax. 
Plate XV., Fig. 1, 1°. 
Bull. Mus. Comp. Zodl., XXIV. 174, 1898. 
In this pretty species the whole upper surface of the carapace is crossed 
by piliferous plications or rug which are broken and irregular on the ante- 
rior half of the carapace, but posteriorly they extend across the whole upper 
surface without a break. The length of the carapace is equal to the breadth, 
the front is prominent, somewhat deflexed, not trifid; a longitudinal median 
suleus extends back some distance on the gastric region. The supraorbital 
margin is convex and thickened, separated from the front by a deep groove ; 
the posterior angle of the orbit is obtuse, but denticulated. On the lateral 
margin of the carapace a minute spine is discernible just behind the cervical 
groove. The pterygostomian region is clothed with a dense pubescence. 
The basal joint of the antenna has a prominent denticulated lobe on its inner 
side. Chelipeds: merus rugose, armed with a strong tooth on the distal 
internal angle; carpus long, thickly set with flat, squamous tubercles both 
above and below, anterior border three-toothed, upper surface with two lon- 
