g4 BULLETIN 76, UNITED STATES NATIONAL MUSEUM. 



^'ll^ilUi()n3 due to size are shown in the following table: 



Table showing variations due to size in Astropecten californicus. 



Besides variations in dimensions, some specimens have the superomarginal 

 plates encroaching onto abactinal surface more than others, especially at base of 

 rav; and the paxilhe vary slightly in specimens of the same size. Some examples 

 have the paxillte more crowded ami their spinelets may be shorter and more granuU- 

 form, as well as thicker in cahber. This causes the paxilla itself to appear more 

 compact and alters somewhat the general facies of the specimen. In specimens 

 with slender paxillar spinelets the abactinal area is more open on the rays. The 

 flattened granules on the superomarginal plates are coarser in some specimens than 

 others. The outer actinal adambulacral spines vary somewhat in arrangement, 

 but the enlarged spine is always flattened in a longitudinal plane and has a round 

 or subtruncate tip. 



Young. — The young of course have shorter arms, fewer marginal plates, and 

 smaller paxilla?. In a specimen with R=20 mm. (r = 6 mm.; R = 3.3 r) there are 

 four or five transverse rows of abactinal paxilla; opposite every two superomarginals 

 at base of ray, and about twelve to fifteen paxillse in a transverse row opposite 

 second superomarginal. These are smaller than in a corresponding example of 

 A. ornati^simus, tiie smaller and more irregular paxillte of the midradial line and 

 center of disk of californicm being particularly well marked. In ornatissimus there 

 is no difference in the midradial region. Lateral spines in examples of this size are 

 one to three, the auxiliaiy lateral spines bemg poorly developed or absent. (Com- 

 pare with corresponding stage of o?matissimus) . Actinal inferomargmal spinelets 

 are inconspicuous, and frequently there is only one series of actinal adambulacral 

 spines, the enlarged spine being not nearly so well developed as in the corresponding 

 stage of ornatissimus. The third series when jjresent is represented by one or two 

 spinelets slightly shorter than those of first or iimer actinal series. Most of the 

 small specimens have a pronunent epiproctal cone. 



Type. — Xo. 1.57, Stanford University invertebrate collection. 



Type-locality.— yionterey Bay, California; 70 fathoms (approximately). 



Distribution.— From north of Bodega Head (north of Point Reyes), California, 

 to Lower California; 10 to 244 fathoms. This species is one of the commonest in the 

 shallower depths of Monterey Bay as determined by the steamer Albatross in 1904. 

 It is abundant also off San Pedro, where it has been collected m considerable num- 

 bers by the staff of the Biological Station of the University of California (1901). 



