910 Stimpson on the Crustacea and Echinodermata 
SPHZROMA AMPLICAUDA. Stimpson. 
FE XADEÉLL 
Sphzeroma amplicauda, Stimpson; Proc. Bost. Soc. Nat. Hist. vi. 89. 
Body gradually widening from the head backwards. 
Thorax transversely ridged, the ridges corresponding in 
number to the segments; and provided with three (some- 
times five) longitudinal rows of small tubercles, those of the 
middle row becoming gradually larger posteriorly, the termi- 
nal one subspiniform, pointing backward. Epimeral pieces, 
distinct and well separated, especially those of the posterior 
segments, and thickened so as to give a raised margin to 
the thorax. Abdomen large, forming two fifths of the 
length of the body, triangular, terminating in an acute 
point; segments all coalescent with the exception of the 
first, next the abdomen, which is distinctly separate, and 
bears a tubercle on either side in the line of those of the 
thorax. There are sometimes also two slight, approximated 
tuberculous ridges, along the middle of the anterior half of 
the caudal plate. Lamelle of posterior pair of false feet 
very large, much expanded, but not extending posteriorly 
beyond the extremity of the abdominal plate; the exterior 
margin of the outer lamella is anteriorly much reflexed. 
The antennz in this species are rather long. 
Dimensions,—Length, 2 a - 
Breadth at seventh thoracic segment, pis u 
0. 
* . of caudal extremity including appendages, 
The epimera in this species are much more distinct than 
is usual in the genus. A few specimens were found adher- 
ing to some fragments of star-fishes picked up on the beach 
of Tomales Bay, by Mr. Samuels. 
Mus. Smithsonian. 
