362 



BULLETIN 76, UNITED STATES NATIONAL MUSEUM. 



Specimens examined. — Thirty-nine, from the following stations: 

 Specimens of Pteraster tesselatus examined. 



2862. 

 3213. 



3202. 

 3274. 



3461. 

 3486. 

 4205. 

 4209. 

 4222. 

 4235. 

 4285. 

 4289. 

 4777. 



Hagemeister Island, Alaska. 

 Shumagin Islands, .\laska. . . 

 Unalaska, Alaska 



Bering Island 



Popof Straits, Shumagins . . 

 Victoria, British Columbia. 



Barclay Sound, British Columbia. 



Departure Bay, Nanaimo, British 



Columbia. 



Ofl Vancouver Island 



South of Alaskan Peninsula (San- 



nak Islands). 

 South of Uniraak Island, Alaska. 



Near Unimak Island, Alaska 



South of Alaska Peninsula (east 



of Unimak Island). 



Straits of Fuca, Washington 



Bering Sea, west of Pribilofs 



Vicinity of Port Townsend, Wash- 

 ....do 



.do. 



Vicinity of Yes Bay, Bchm Canal 

 Chignik Bay, .\laskan Peninsula. 



Uyak Bay, Kadiak 



Near Semisopochnoi Island, Aleu- 

 tians. 



.do. 



4784 Near Attu Island , Aleutians. 



Fathoms 

 8-15 



Extra low 

 water. 



130-193 

 31-59 

 74-80 



Nature of bottom. 



gray sand, pebbles, 

 black sand 



....do 



black stones, rocks . 

 black sand, shells. . 



gray sand, gravel 



green mud, fine sand 



rocks, shells 



rocks, coarse sand, shells, 

 gray sand, broken shells. 



gray mud 



gray sand, shells 



gray mud 



fine gravel , 



broken shells, pebbles, 



sand, 

 coarse pebbles 



U. S. Nat. Mus., W. H. Dall. 

 Do. 

 Do. 



U. S. Nat. Mus. 



U. S. Nat. Mus., \V. II. Dall. 



U. S. Nat. Mus., C. ¥. New- 

 combe- 



U. S. Nat. Mus., Altatrott, 

 1889. 



U. S. Nat. Mus., Geo. W. 

 Taylor. 



U. S. Nat. Mus. 



Albatross, 1903. 



Do. 

 Do. 



Remarks. — It may eventually be considered advisable to place this and the 

 follo\v-ing form in the genus Retaster. Practically all the current diagnoses of 

 RetaMer read as if Pteraster never had a dorsal reticulum, or else as if deposits in the 

 supradorsal membrane characterized Pteraster. Many species of Pteraster entirely 

 lack the spicules. So far as the reticulum is concerned, the difference between the 

 two genera is one of degree rather than kind. Species that may be considered 

 typical members of RetaMer are capensis, cribrosus, gibber, and insignis. These have 

 the muscle bands conspicuously developed, dividing the membrane into areas 

 sharply circumscribing the spiracula. Just this is found in tesselatus, but the muscle 

 bands are not usually conspicuous, except on the sides of the body (and elsewhere 

 in specimens in wliich the epidermis is more or less rubbed). The narrow actino- 

 lateral membrane is not characteristic of Retaster, since several undoubted Pteraster 

 also possess it. All known Retaster (excluding Diplopteraster) , however, have the 

 narrow membrane. 



In the following subspecies, or it may be, closely related species, the reticula- 

 tions are not evident superficially in the unique specimen. Neither are the spira- 



