358 



CLARK. 



each about 5 mm. long, and there is no evidence as yet of new arms 

 forming. Of course, these pecuharities are due to the autotomous 

 asexual reproduction, characteristic of the genus. There is no clue 

 to what the color in life mav have been. 



Stolasterias tenuispina. 



Asterias tenuispina Lamarck, 1816. Anim. s. Vert., 2, p. 561. 

 Asterias (Stolasterias) tenuispina Sladen, 1889. Challenger Asteroidea, pp. 

 563, 583. 



This species has long been known from Bermuda, where it is de- 

 cidedly the most common sea-star, so its occurrence on the Chal- 

 lenger Bank is not surprising. It is worthy of note, however, that 

 the specimens collected in 1903 are all very small, the largest of the 

 five being only 13 mm. across its six arms. One has seven arms, 

 while the smallest, which is obviously the result of a recent autoto- 

 mous division, has but three. 



Coronaster briareus. 



Asterias briareus Verrill, 1882. Amer. Jour. Sci., 23, p. 220. 

 Coronaster briareus Verrill, 1914. Monograph of the Shallow-water Starfishes 

 of the North Pacific Coast, p. 49. 



The occurrence of this rare sea-star on the Challenger Bank is not 

 surprising, as it has previously been recorded both north and south of 

 that latitude and has been taken at least once in quite as shallow water. 

 Nevertheless the specimen in the present collection is notable, for it 

 is not only of unusually large size but it has an extraordinarily large 

 number of arms. There are six arms on one side of the disk, 110-125 

 mm. long, while on the other side are two sets, one of five and one of 

 four arms, 10-16 mm. long. The inner two arms of the set of five lie 

 somewhat above the inner arms of the set of four, as though one series 

 overlapped the other. Verrill says the "rays" are "variable in num- 

 ber, ten to twelve in the larger specimens; one of the larger has the 

 radii 8 mm. and 76 mm.; ratio 1 : 9.5." (1915, Bull. Univ. Iowa: Nat. 

 Hist., 7, p. 31). In the present 15-rayed individual, the lesser radius 

 is about 8 mm. Since the greater radius is 110-125, the ratio is some- 

 thing like 1 : 13-16, or as it is more usually expressed R = 13-16r. 

 The color of the alcoholic specimen is the usual yellowish of bleached 

 material and there is no indication of what the color may have been 

 in life. Perrier's figure -of C. ixirfaiti (1894, Trav. et Tab, Stell., pi. 



