340 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 8 



Brisaster townsendi (A. Agassiz) 



Plate 64, Fig. 64 

 Schizastcr toicnsendi A. Agassiz, 1898, p. 82. 

 Schizostcr (Brisaster) townsendi Mortensen, 1907, pt. 2, p. 123. 

 Brisaster townsendi H. L. Clark, 1917, p. 179, pi. 155, figs. 4, 6, 8. 



A common Spatangoid of the Eastern Pacific between southern Alaska 

 and the Galapagos Islands, this species was taken by the Velero at 14 sta- 

 tions. The largest of the 120 specimens is badly damaged but measures 60 

 mm in width and must have been about 70 mm long and some 30 mm high. 

 The smallest is 7 x 5.5 mm. All are some shade of brown, ranging from a 

 very light shade, with fascicles conspicuously darker (Station 1163-40, 

 215-225 fms) to a very dark brown, the fascioles more or less conspicuous 

 (Station 1497-42, 60-74 fms). 



The specimens from Station 1133-40, of? Redondo Beach, California, 

 in 49-172 fms are remarkable for having the lateroanal fasciole developed 

 as a conspicuous band more or less closely surrounding the anus, not in any 

 sense lateral. At several stations both Brisaster and Brissopsis occur and it 

 seems probable that some of the puzzling specimens are hybrids. In his full 

 decription of this Brisaster, Agassiz (1904) refers to the shape of the 

 young when 10 mm in diameter. Some of the Velero specimens are smaller 

 than that and have a very striking pentagonal form. These young pen- 

 tagonal individuals have the sides of the pentagon measuring 5 or 6 mm. 

 The peripetalous fasciole follows the margin of the pentagon on the upper 

 side. Ventrally each interambulacrum is a convex bulge, the posterior 

 (subanal) one somewhat the largest. The mouth is but little anterior to 

 the center, and there is no definite sternum. 



Distribution. — The Velero took Brisaster at stations ranging from 

 Oregon (Station 1497-42, Lat. 44° 49' 10'' N) to southern California 

 (Station 1223-41, Lat. 33°, 27' 10" N), at depths of 20-250 fms, but the 

 bulk of the specimens are from the vicinity of the Channel Islands in 

 depths of more than a hundred fathoms. The greatest depth was in San 

 Pedro Channel at 225-250 fms. Off Redondo Beach specimens were taken 

 at 49-172 fms and off Santa Cruz Island in 64-134 fms. The absence of 

 Brisaster from stations further south is no doubt due to the little dredging 

 the Velero did at greater depths than 150 fms, for the Albatross material 

 on which the species is based was collected at depths of 146-995 fms at 

 stations from the Gulf of California to Panama. Other records extend the 

 range north to southeastern Alaska. 



Type.—M.C.Z. no. 2961 (CotA^e). 



Type locality. — Gulf of Panama to Guaymas, Mexico. 



Depth.— 20-9% fms. 



Specimens examined.— 120 specimens from 14 stations. 



