2l8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 52 



HIMEROMETRA ECHINUS, new species 



Centro-dorsal discoidal, the moderately large polar area slightly 

 concave; cirri arranged in two closely crowded, more or less alter- 

 nating rows. 



Cirri xxiv, 26-30; first four joints about twice as broad as long, 

 sixth squarish, seventh to tenth or eleventh about one-third longer 

 than broad, then becoming squarish again, and, in the terminal 

 twelve or fourteen, broader than long; tenth and following joints 

 with large dorsal spines; opposing spine terminally situated, erect, 

 about half as long as the diameter of the penultimate joint ; terminal 

 claw rather longer than the penultimate joint, slender, and moder- 

 ately curved. 



Radials projecting slightly beyond the centro-dorsal ; first costals 

 trapezoidal, proximally about four times, distally about three times 

 as broad as long, united in their basal third, but diverging very 

 rapidly from their point of union, so that the free lateral border of 

 two adjacent first costals forms a moderately curved even line; 

 costal axillaries broadly pentagonal, nearly twice as broad as long, 

 with large and broad ventro-lateral projections; distichals, palmars, 

 and post-palmars 2, bearing on the outer side of the rays, in common 

 with the first brachials, large and broad ventro-lateral processes. 

 Forty arms in the type (one interior palmar series being absent, but 

 its loss compensated by the development of an external post-palmar 

 series on the same distichium) ; first nine or ten brachials discoidal, 

 or very slightly-wedge-shaped, about twice as broad as long, then 

 becoming short-triangular, rather more than twice as broad as long, 

 and short-wedge-shaped in the distal portion of the arms. Syzygies 

 occur between the twenty-second and twenty-third to thirty-second 

 and thirty-third (most commonly in the vicinity of the twenty-third) 

 brachials, and distally at intervals of 9 to 24 (usually g to 13) 

 oblique muscular articulating. 



First pinnule 15 mm. long, large, stiff, and spine-like, resembling 

 ^he second, with 115 joints, the first two nearly twice as broad as 

 long, the third squarish, then increasing in length, the seventh and 

 following being from once and one-half times to nearly twice as 

 long as wide; second pinnule 16 mm. long, with 12 or 13 joints, of 

 which the distal are rather longer than those of the first; third pin- 

 nule 15 mm. long, resembling the second; fourth, 12 mm. long, with 

 II joints, resembling the third: following pinnules decreasing in 

 length and also slightly in stoutness, the seventh being 7 mm. long, 

 with 10 joints, then gradually losing their peculiar stiffness, and 



