Verrill, Notes on Madiata. 287 



rays, form only a single series, alternately larger and smaller, tlie 

 larger ones broad, flat, truncated. Outside of these a row of larger 

 ones, similar in form, but much stouter. 



This form, which does not appear to be a distinct species, may be 

 Linckla hifascialis Gray. It occurs, also, at Cape St. Lucas. 



Ophidiaster pyramidatns Gray. 



Ophidiaster (Pharia) pyramidatus Gray, Ann. and Mag. Nat. Hist., 1840. 

 Ophidiaster porosissimus Liitken, op. cit., 1859. 



Mr. Bradley has sent numerous specimens of this species from Pan- 

 ama and the Pearl Islands. We have also received specimens from 

 the Smithsonian Institution collected at Cape St. Lucas by J. Xantus. 

 Dr. Gray's specimens came from the Bay of Caraccas, West Columbia, 

 on rocks, — Hugh Cuming. Dr. Liitken received his from Puntarenas. 

 It therefore has, like the last species, a range extending through the 

 whole extent of the Panamic Zoological Province. It occurs on the 

 reef at Panama, with the last, at extreme low-water of spring tides, 

 among rocks. 



The original description by Dr. Gray is as follows : " Rays suban- 

 gular, elongate, nearly four times as long as the width of the pyram- 

 idal body, with seven rows of tubercles ; the central dorsal series 

 much the largest ; spines near the ambulacra ovate, subacute." 

 • Our numerous specimens show that the pyramidal form of the body 

 is merely due to the state of preservation, the specimens in alcohol 

 showing little or nothing of this character, while in a part of the 

 dried specimens it is pretty well marked. 



The ratio of the greater to the smaller radius is as 7 or 8; 1. A 

 specimen, with rays 4*6 inches long, has the radius of the disk '6 ; 

 width of rays at base '7 ; elevation of dorsal surface of disk '9. 



The rays are rounded, somewhat swollen, tapering very slowly to 

 the thick, obtuse, rounded ends. The rays, in small specimens, and 

 those that are in the process of restoration after being broken, have 

 more acute tips. 



The interarabulacral plates bear two elongated, blunt spines on the 

 inner edge, of which the one nearest the mouth is a little longer than 

 the other and twice as thick, flattened and subclavate at the ends. 

 These form a single, crowded row of alternately larger and smaller 

 spines along the edges of the ambulacral furrows. Outside of these 

 there is a row of distant, short, stout spines, blunt at the ends and 

 narrow at the bases, which arise from the outer part of every second 

 or third plate. Joining the outer edges of the interambulacral plates 

 there is a close row of stout, somewhat convex plates. At intervals 



Trans. Connecticut Acad., Vol. I. 37 April, i867. 



