54 



bulletin: museum of comparative zoology. 



acters clearly, and cannot always be distinguished certainly from mainland Heli- 

 asters of the same size. So far as the material at hand is concerned, the specimens 

 from the different islands of the archipelago are quite indistinguishable, with the 

 single interesting exception of the specimen from Abingdon Island. This indi- 

 vidual is not adult, but has 35 rays and is unusually well preserved. The rays are 

 remarkably slender, much as they are in some very young specimens of micro- 

 brachius. When compared with a specimen of the same size from Charles Island, 

 the peculiarities of this Abingdon Island individual are well brought out. 



Locality of Specimen. 



Charles Island 

 Abingdon Island 



R. 



46 mm. 

 44 " 



Breadth of ray 

 at base. 



6 mm. 

 4 " 



Breadth in R. 



7.7 times 

 11 



Breadth in free 

 portion of ray. 



1.6 tinfes 



2.7 " 



Material examined : — 



6 specimens. Albemarle Island. 

 25 " 

 1 specimen. " " 



1 " Abingdon 



6 specimens. Charles " 



6 " Chatham 



?3 " Loc? 



Leland Stanford Jr. Univ. Collection. 



U. S. N. M. 



M. C. Z. 



U. S. N. M. 



M. C. Z. 



U. S. N. M. 



« « 



48 specimens 5 localities 



Heliaster polybrachius, sp. nov. 



Plate 3, Fig. 2 ; Plate 7, Fig. 13 ; Plate 8, Fig. 8. 



Heliaster Cumingii Verrill, 1867a, p. 291 ; 1867b, p. 33, line 10, 334 and 344. 

 Perrier, 1878, p. 11 and 99. 

 Leipoldt, 1895. 



Description. — Rays 31-43, averaging (38 adults) 37.1; about 18 (14-23) per 

 cent of ray, free. R = 55-90 mm. ; r = 45-77 mm. Breadth of ray at base, 

 9-11 mm. R = 0-8 br. Rays much as in cumingii, but free portions stouter as 

 a rule, with more convex sides and blunter tip. Disc as in cumingii, but abactinal 

 spines much more numerous, especially on the region where disc and rays join, 

 25-50 per sq. cm. Marginal series of spines on rays very distinct, but not usually 

 noticeably larger than other abactinal spines. All of the abactinal spines are 

 commonly low, of nearly uniform height, and more or less distinctly capitate. 1 

 Actinal surface as in cumingii, but pedieellariae are commonly abundant among 

 the adambulacral and adjoining spines. Pedieellariae all small, as in cumingii. 

 Buccal depression, pedicels, and madreporite also as in cumingii. — Color of abac- 



1 Leipoldt (1895) refers to a specimen in which the abactinal spines were three 

 millimeters high, but none of the specimens before me have any over two, and they 

 are commonly about one millimeter high. 



