NEW STARFISHES FROM THE PACIFIC COAST 131 



short spinelets; proximal marginal plates strictly actinal in 

 position; adambulacral plates with usually four actinal spines. 

 Papulae very conspicuous; abactinal skeleton more open. 



Crossaster alternatus. 

 aa. Marginal plates of one kind, viz. : conspicuous transversely 

 oriented paxilliform plates which are strictly marginal in posi- 

 tion ; adambulacral plates with 2 or 3 actinal spines. Abactinal 

 skeleton less open Crossaster borealis. 



CROSSASTER ALTERNATUS Fisher, new species. 



Rays 10. R =63 mm.; r = 24 ; R=2.6r. A larger speci- 

 men taken between San Diego and San Clemente (500 fathoms) 

 in 1904 measures as follows: R = 100 mm.; r — 34 mm.; 

 R= 2.gr. Breadth of ray at base, 23 mm. 



General form flattened ; abactinal surface of disk slightly 

 convex, capable of inflation, but flattened on central part; 

 abactinal surface of rays slightly rounded ; margins well 

 rounded ; actinal surface nearly flat ; interbrachial angles rather 

 acute ; abactinal skeleton open reticulate, the ossicles slenderer 

 than in Crossaste?' fiafifiosus ; papulae large; paxillas small, 

 well-spaced ; marginal plates characteristic, more prominently 

 spinous transversely placed plates alternating with (usually 2) 

 longitudinally oriented plates with very short spinelets ; marginal 

 plates actinal in position on basal half of ray ; actinal interradial 

 areas small, with few plates set fairly close together ; a single 

 series of very small intermediate plates extending to end of 

 ray ; adambulacral plates with 4 to 8 furrow spinules and a 

 transverse series of 4 actinal spinules. 



Abactinal integument rather thin but tough and pliable, 

 parchment-like, quite opaque and obscuring the ossicles unless 

 dried. Skeleton open and forming a net-work with fairly wide 

 meshes, which are irregular and largest on disk ; connecting 

 ossicles slender, often irregular; enclosed within meshes, small 

 free irregular ossicles ; these often absent, but usually present 

 on disk and most numerous near its center. Paxillas with a 2- 

 to 4-slender-lobed base and a low stout pedicel surmounted by 

 usually 4 or 5 rough, delicate tapering, pointed, spinelets en- 

 closed in a delicate membraneous sac, which fits tightly about 



