510 Stimpson on the Crustacea and Echinodermata 



SPILEROMA AMPLICAUDA. Stimpson. 



PL XXIII. f.l. 



Sphasroma 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. Lamellae 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 antennae in this species are rather long. 



Dimensions, — Length, 0.25 inch 



Breadth at seventh thoracic segment, 0.119 " 



" of caudal extremity including appendages, 0.17 " 



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. 



