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



ECHINODERMATA 



29 



and provided with a high and broad ridge along the 

 medianline, where they are united. Six long, thin papillae 

 united by a membrane are arranged in a row along the 

 horizontal edge of the mouth plates. Secondary papillae 

 on the actinal surface of the plates are wanting. 



The colour in life of the best preserved specimen 

 was a deep purple red, on the abactinal surface of which 

 a slight tinge still remained. The actinal surface and the 

 tube-feet were pale red. The other specimen had com- 

 pletely lost its colour. The third specimen, preserved in 

 formol, was ash-grey on the abactinal surface and light 

 reddish gray on the actinal surface, the tube-feet red- 

 dish grey. 



Numerous light reddish grey eggs with a diameter 

 of 0.6 mm. were found in the interradial spaces. 



I have referred the specimens to Pteraster reductus 

 Koehler as they agreed with that species in most charac- 

 teristics e. g. in the number of mouth- and adambulcral- 

 papillae, as well as in number of actino-lateral beams. 

 But they differ from the typical P. reductus in that their 

 third actino-lateral beam was longest while in Koehlers 

 species the 4th was longest. Moreover the typical P. 

 reductus has longer arms, its arm-radius according to 

 Koehler being twice the length of disc-radius. Judging 

 from Pteraster militaris no great importance is to be 

 attached to this difference, however. Koehlers coloured 

 illustrations of P. reductus 1 ) likewise differ from the colour 

 of the best preserved one of the specimens in question. 

 But this difference of colour is of no more importance 

 than the relative length of arms. 



Pteraster reductus was found 1888 by the Prince of 

 Monaco off the Azores and was likewise taken there by 

 him in 1896 and 97. By the find of the "Michael Sars" 

 its horizontal distribution will be from 34° 59' to 41° 40' 

 41" N. and from 26° 26' 15" to 33° 1' W. The bathymetrical 

 distribution is from 1846 to 2870 m. 



Hymenaster pellucidus Wyville Thomson. 

 Hymenaster pellucidus Wyville Thomson, The Depths of the Sea, 1873, 



p. 220. 



9 /s— ,0 /8, stat. 102, 60° 57' N. 4° 38' W., 1098 m., dark sand and 

 clay, temp, h- 0.9° Cel. A somewhat damaged specimen, measuring: 

 arm-radius 29 mm., disc-radius 17 mm., r:R = 1 : 1.7. 



The specimen had two adambulacral papillae and two 

 pair of secondary mouth-papillae. Number of primary 

 mouth papillae four. Kalischewskij 2 ) has etablished a 



variety arctica of this species with three pairs of secondary 

 mouth papillae, but his illustration shows only two pairs, 

 which is what the typical form has. I agree wiht Koeh- 

 ler 1 ) that these two forms can not be separated. An 

 examination of the specimen collected by the "Voeringen" 

 and the "Michael Sars" shows that the mouth-plates 

 have 1 — 3 secondary papillae 2 ). 



Hymenaster pellucidus is indigenous to the Nor- 

 wegian Sea and adjacent waters where it ranges from 

 the Faroe— Shetland Channel (60°21'N., to 81°1'N. and 

 from the east coast of Greenland, (Forsbladfjord, about 

 26° W.) to 114° 31' E. Perrier besides records it from the 

 Azores 3 ). I am inclined to think, however, that he con- 

 fused it with another species. The bathymetrical distri- 

 bution is 27 to 2814 m. Most of the localities of this 

 species belong of the cold area, but it seems to invade 

 the warm area to some extent, as the temperatures records 

 vary between -=- 1.7° ("Jermak") and 3.36° ("Michael Sars" 

 1902, stat. 86) i ). The warm water stations, however, lie 

 close to the limit of the cold area, and the hydrographical 

 conditions may probably therefore vary there. 



Hymenaster rex Ed. Perrier. 

 Hymenaster rex Ed. Perrier, Ann. Sci. Nat., ser. 6, Zool., vol. 

 19, 1885, no. 8, p. 69. 



7s, stat. 25 A, 35° 36' N. 8° 25' W., 2300 yellow mud. Two spec- 

 imens, measuring : 



Arm-radius 32 mm. 43 mm. 



Disc-radius 25 „ 37 „ 



r:R 1 : 1.23 1 : 1.16 



The adambulacral plates have three papillae of which 

 the adoral one is largest. The mouth-plates bear two 

 pairs of secondary papillae and three papillae along their 

 free border and one of the mouth-plates of the largest 

 specimen had even 4 primary papillae. Some 20 actino- 

 lateral spines were counted. The valves around the oscu- 

 lum have 10—12 spines. The colour of the specimens 

 in alcohol is grayish-red on abactinal surface, slightly 

 darker on the interradial than on the radial surface. 

 The actinal surface is dark violet, the tube-feet bluish white. 



') Koehler: Echinodermes, Res. Camp. Sci. Monaco, Fasc 34, 

 1909, tab. 3, fig. 8 & 9. 



2 ) Kalischewskij : Zur Kenntnis d. Echinodermfauna d. sibir. 

 Eismeeres, Mem. Acad. Imp. Sci. St. Petersbourg, ser. 8. vol. 18, nr. 4, 

 1907, p. 36, tab. 1, fig. 9. 



') Koehler: Echinoderms, Res. Camp. Sci. Monaco, Fasc. 34, 1919 

 p. 93. 



2 ) Grieg: Invertebres du Fond, Due d'Orleans: Croisiere Oceano- 

 grafique, 1909, p. 54. 



3 ) Ed. Perrier: Stellerides, Res. Camp. Sci. Monaco, Fasc. 11, 

 1896, p. 40. 



*) The recorded temperatures are: "Porcupine" -=- 1.3°, "Voe- 

 ringen" ~ 1.3—1.1°, "Michael Sars" 1900 -f- 1-0.11°, 1902-^0.32° 

 —3.36°, "Thor" -f- 0.58°, "Belgica" 0.4°, the Russian Spitzbergen 

 Expeditions -=- 1.1—0.3°, "Jermak" -=- 1.7—3.1°, "Varna" -f- 1.4—1.2° 

 The temperatures varied between -=- 0.8 and -f- 1.5° at the depths 

 in the Kara Sea, 84—116 m., where the "Dijmphna" found this species. 



