Pacific Coast of North America. 



177 



margin of this segment. The terminal segment is subtriangular 

 in sliapp, with a broad funnel-like excavation at its extremity, 

 formed by the infolding of the lateral edges. The anterior 

 part of the terniinal segment is very convex, upon which 

 elevation are situated three large tubercles in a transverse row, 

 the centre one being in the median line. At the base of the 

 terminal excavation is also a small tubercle. Both branches 

 of the uropoda are similaily shaped, being of the same width 

 throughout their entire length and rounded posteriorly. The 

 outer branch is somewhat shorter than the inner branch ; 

 neither reaches the extremity of the abdomen. 



Individuals were found at Gualala, California, on Ilaliotis 

 rvfescens, by Dr. E,. E. G. Stearns ; also one specimen at 

 Catalina Harbour, California, and one at Popoff Island, 

 Aleutian Islands, at low water, by Mr. W. H. Dall. 



Tijpe. No. 22569, U.S. N. M. Popoff Island, Aleutian 

 Islands. 



23. Dynamene henedicti, sp. n. 



Body oblong, oval ; surface minutely granular ; colour 

 dark grey. 



Head with small median point. Eyes situated post- 

 laterally. First pair of antennae extend to the middle of the 

 first thoracic segment ; first joint of peduncle longest ; second 

 and third joints about equal in 

 length ; flagellum contains six 

 joints. Second pair of antennte 

 extend to the posterior margin of 

 the second thoracic segment ; fla- 

 gellum contains about eleven joints. 



The thoracic segments are of 

 equal length. The epimera are 

 square, with rounded posterior 

 angles. 



The penultimate abdominal seg- 

 ment is crossed by suture-lines 

 indicative of coalesced segments. 



The terminal segment is triangular, terminating posteriorly 

 in two teeth separated by a narrow, rounded, funnel-shaped 

 sinus. This segment is very convex, and bears two longi- 

 tudinal ridges on either side of the median line. The uropoda 

 do not exceed in length the extremity of the terminal seg- 

 ment. Both branches are rounded posteriorly and are similar 

 in shape and size. 



The type was collected by Mr. Heath at Monterey Bay, 

 California, at the surface. No. 22570, U.S. N. M. 



Fig. 10. 



Di/namene henedicti. X 13J. 

 Last thoracic segment and 

 abdomen. 



