SHALLOW- WATER STARFISHES 



PTERASTER MULTISPINUS Clark. 



Pteraster tnultispinus H. L. CLARK, Proc. Boston Soc. Nat. Hist., xxix, No. 15, 

 p. 326, pi. in, figs, i, 2, 1901. Fisher, op. cit, 191 i&, p. 359 (description 

 copied from Clark). 



The type specimen, which I have studied in the collections of 

 Columbia University, is a small five-rayed specimen, with short, 

 tapered, subacute rays, broader than long, with the small tips turned 

 up a little at the ends. Radii, 18 mm. and 27 mm.; ratio, i: 1.5. 

 It is probably young; it is preserved in alcohol. 



Disk a little convex, covered with small, numerous, slightly pro- 

 jecting spinules; there is no defined margin, the borders being 

 rounded and the dorsal membrane continuous to the under side in the 

 interradial areas. The dorsal membrane is rather firm, with very 

 small spiracular pores, inconspicuous except distally on the rays. 

 Pseudopaxillae are hour-glass shaped, rather high, bearing eight to 

 ten, or often more, spinules. Oscular opening rather large, sur- 

 rounded by five clusters of webbed spines, about six in each group, 

 the central ones larger. 



Ambulacral feet in two rows. Adambulacral fans of spines are 

 oblique, each with five or six spines, webbed to the tips. The inner 

 one is much the shortest; the outer three are longest. Appressed 

 retroambulacral spines are mostly short. Therefore there is no 

 marginal free edge with a fringe of spine-tips along the rays, such 

 as is conspicuous in P. militaris and many other species, but some 

 of the spines in the interradial areas are rather long and slender. 



Peroral spines slender, six on each angle of the jaw, webbed 

 together. Epiorals two, rather large, slightly swollen distally at 

 the translucent part; tips acute. Peractinal or segmental pores 

 with a narrow spmiform valve, as seen edgewise, in natural position. 



( ?) Puget Sound (Columbia University Expedition, 1897). 



This looks very much like a young specimen of P. tesselatus, 

 younger than any of the latter that I have seen. The apparent lack 

 of numerous spiracles on the disk is due to the strong contraction of 

 the integument in alcohol. It often occurs in P. tesselatus also. 



PTERASTER GRACILIS (Clark) Verrill. 



Retaster gracilis H. L. CLARK, Proc. Boston Soc. Nat. Hist., xxix, p. 326, 



pi. in, figs. 3, 4, 1897. 

 Pteraster gracilis VERRILL, op. cit., 1909, p. 555. Fisher, op. cit., 1911, p. 349 



(description copied from Clark). 



This is a five-rayed species, of which I have studied the type at 

 Columbia University. It has the radii about 9 mm. and 18 mm. 



