ATLANT. DEEP-SEA EXPED. 1910 VOL. Ill] 



ECHINODERMATA 



25 



that the relative length as well as breadth of arm are 

 subject to great variations and judging from the material 

 at my disposal, older individuals appear to have propor- 

 tionately longer and more slender arms than younger 

 ones, the ratio, hovewer, being subject to individual 

 variations. 



The colour in life was pink or white. 



Zoroaster fulgens was discovered by the "Porcupine" 

 in 1869 north-west of the Hebrides, 992—1304 m. It was 

 later taken on the east Atlantic side south of Iceland by 

 the "Thor" (921 m.), in the Faroe — Shetland Channel by 

 the "Triton" (1016—1043 m.) and the "Michael Sars" 

 (1100—1300 m.), west of Ireland (732—1797 m.) by the 

 "Flying Falcon" and the "Helga"; in the Bay of Biscay, 

 1300 m. by the "Caudan" as well as by the "Travailleur" 

 and the "Talisman" between 23° and 44° N., 912 -1975 m. 

 On the west Atlantic side the "Challenger" found it off 

 North America, 2287—2470 m. and off Pernambuco, 

 1235 m. The "Michael Sars" obtained it east of New 

 Foundland, 120 m. Thus Zoroaster fulgens ranges from 

 23° to 62° 57' N. on the east Atlantic side and from 

 8°37'S. to 47°16'N. on the west Atlantic side. The 

 bathymetrical distribution is 732 to 2470 m., there is 

 besides one specimen from a depth of only 120 m. The 

 bottom temperatures at the localities, where temperature 

 measurements were made, are: "Porcupine" 5.2°, "Chal- 

 lenger" 3.3—4.4°, "Triton" 7.5—7.6°, "Michael Sars" 3.3— 

 8.07°. It will be seen from the foregoing that Zoro- 

 aster fulgens is a true warm-water species. It must 

 therefore be due to a mistake, as stated before, when 

 a specimen of this species was recorded from stat. 102 

 which belongs to the cold area of the Faroe— Shetland 

 Channel. The specimen must have been left in the 

 trawl from stat. 101, where several specimen of this 

 species were taken. The same must have been the case 

 as regards Plutonaster bifrons and Psllaster andromeda 

 of both of which a very defective and macerated specimen 

 exists from stat. 102, while several specimens were taken 

 at stat. 101. Like Zoroaster fulgens they are true warm- 

 water species as stated before, and do not belong to the 

 cold area of the Norwegian Sea. The other echinoderms 

 taken at stat. 102, viz: Pontaster tenulspinus vat: plaly- 

 nota, Solaster papposus var. septentrlonalis, Solaster 

 squamatus, Ophiopleura borealis, Ophioscolex glacialis 

 and Hathrometra prolixa are on the contrary decided 

 arctic and boreo-arctic species. The same is true of the 

 others invertebrates found at stat. 102, which I may men- 

 tion : — Buccinum hydrophanum, Neptunea carta, Neptunea 

 mohni, Philene finmarcklca, Cuthonella abyssicola, Scal- 

 pellum angustum, Colossendeis proboscidea, Colossendeis 

 angusta, Nymphon grossipes, Borenymphon robustum etc. 



Solaster abyssicola Verrill. 



(PI. 5 figs. 2—4) 



Solaster abyssicola Verrill, Amer. Journ., ser. 3, vol. 29, 1885, p. 152 



and Ann. Rep. U.S. Fish. Comm. 1885, p. 541. 



18 /7, stat. 88, 45° 26' N. 25° 45' W., 3120 m., sand and yellow mud, 

 temp. 2.5° Cel. Two specimens measuring: 



Diameter 103 mm. 137 mm. 



Arm-radius 54 „ 70 „ 



Disc-radius 22 „ 28 „ 



Breadth of arm at base 13—14 „ 15—18 „ 



Height of arm at base 7—9 „ 12—14.5 „ 



r : R 1 : 2.45 1 : 2.5 



Number of arms 8 8 



Number of inner adambulacral- 



papillae 3—4 3—4 



Number of outer adambulacral- 



papillae 3—5 3—5 



The abactinal skeleton is composed of stellate cal- 

 careous plates (pi. 5, fig. 4), whose four branches 

 united with the branches of other plates forming a qua- 

 drate mesh-work. In some of these plates a branch may 

 be absent whereby two mesh-spaces are turned into 

 one larger of oblong rectangular form. Meshwork of 

 irregular or triangular form may also occur, but seems to 

 be comparatively rare. A short cylindrical paxillae in the 

 centre of the plate bear up to about 15 short divergent 

 calcareous spines. The meshwork have normally 3—4 

 large papula;, but the larger ones may have as many as 8. 

 The skeleton of Solaster endeca (pi. 5, fig. 5) consists 

 in part of calcareous plates similar to those of Solaster 

 abyssicola, in part of short narrow calcareous rods. The 

 network formed by the calcareous deposits is of an ex- 

 tremely irregular shape and bears several paxillse, the 

 mesh-spaces bear proportionately to their size from 1 to 

 7 papulae Besides isolated calcareous rods bearing one 

 paxilla may be present in them, similarly as in the mesh- 

 spaces of Solaster papposus. 



The paxillse in the plates of the actinal area are 

 cylindrical and furnished with as many as 8 very small 

 spines. They are arranged in rows and similar to the 

 paxillse of the abactinal skeleton, but smaller. 



The outer row of adambulacral papillae (pi. 5, 'fig. 3) 

 bears 3 — 5 papillae in both specimens, most often 4. They 

 are comparatively short, covered by a thick membrane 

 and united at the base. The inner row bears 3 — 4 papillae 

 of about uniform size and united by a membrane to half 

 their length. 



Solaster abyssicola has according to Verrill 5—7 

 adambulacral papillae, while the two specimens under 

 discussion have only 3 — 5. Notwithstanding this I have 



GRIEG :-ECHINOD. 4 



