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



ECHINODERMATA 



27 



Colour in life orange-red on the abactinal surface 

 with yellowish red paxillse and yellowish white on the 

 actinal surface. 



Solaster squamatus appears to be indigenous to the 

 cold area of the Norwegian Sea from 100—1159 m. It 

 may, however, occasionally make its way a little into the 

 warm area, where the temperature of the bottom-water 

 may be comparatively high, and where the fauna consists 

 mainly of warm-water species. The "Michael Sars" thus 

 found it in 1902 at a locality, (stat. 85, 62°53'N. 9°6'W. 

 450 m., 3.98° Cel.) together with Pentagonaster granulans, 

 Poranlomorpha hispida, Ophiactis abyssicola, Gorgono- 

 cephalus lamarcki, Hathrometra tenella etc. Among other 

 arctic species, besides Solaster squamatus, which were 

 taken at this station, I may mention, Lophaster furclfer, 

 Ophlura sarsi, Ophioplwlis aculeata, Ophiacantha bldentata 

 etc. (cfr. Appelldff: Havbundens dyreliv) 1 ). 



Lophaster turcifer Dtiben & Koren. 



Solaster furcifer Diiben & Koren, Kgl. Vet. Akad. Handl. 1844 (1846) 



p. 243, tab. 6, tigs. 7—10. 



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

 clay, ; temp. -=- 0.9° Cel. Two specimens measuring: 



Diameter 138 mm. 72 mm. 



Arm-radius 73 „ 32 „ 



Disc-radius 31 „ 12 „ 



r : R 1 : 2.36 1 : 2.67 



Number of ventro-marginal paxilla; 25 20 



Number of inner adambulacral 



papilla; 3—5 3—4 



Number of outer adambulacral pa- 

 pills 3—6 3—5 



The specimens belong to the group, which I called 

 the Arctic or cold water form 2 ). Their appearance recalls 

 two specimens, which the Duke of Orleans found in the 

 Kara Sea) 3 . The interbrachial arc is rounded, and the 

 abactinal skeleton consists of irregular stellate deposits, 

 the branches of which unite with those of the adjacent 

 plates, forming a meshwork. A large and robust paxilla 

 is attached to the calcareous deposits, which in the disc- 

 centre of the largest specimen measured about 2 mm. in 

 height and about 1 mm. in diameter and bore as many 

 as 20 spines covered with a thick membrane. The paxillae 

 of the ventro-marginal plates of the interbrachial arc mea- 

 sured about 2 mm. in breadth as well as in height and 



') Hjort: Norges Fiskerier I Norsk Havfiske, 1905, p. 105. Cfr. 

 Murray & Hjort: The Depths of the Ocean, 1912, p. 533. 



'-) Grieg: "Michael Sars" Asteroidea, p. 70. 



3 ) Grieg: Echinodermes, Due d'Orleans: Campagne Arctique 

 de 1907, 1910, p. 17, figs, 11 & 12. 



bore 30 to 40 spines. The paxilla; of the actinal plates 

 had 4—10 spines. 



The colour of the specimens in life was brick-red 

 on the abactinal surface and orange-yellow on the actinal. 



Walter K. Fisher has described two forms of Lopha- 

 ster from the northern part of the Pacific. One of them, 

 Lophaster furcilliger 1 ) ranges from Alaska to southern 

 California and the Galapagos Is. from 351 to 2013 m., 

 the other, Lophaster furcilliger vexator 2 ) inhabits the 

 Bering Sea and ranges south to northern California. Its 

 bathymetrical distribution is from 137 to 640 m., it is 

 most common, however, at depths below 370 m. Fisher 

 states in "Asteroidea of the North Pacific and adjacent 

 Waters, Phanerozonia and Spinulosa" 3 ) where these two 

 forms are described in detail, that the latter form has an 

 intermediary position between L. furcilliger and L. furcifer. 

 From the typical furcifer it differs, "in having a more open 

 abactinal skeleton with consequently more widely-spaced 

 paxilla;, higher paxilla; with longer spinelets, much smaller 

 actinal paxilla; (about as in furcilliger) and longer adam- 

 bulacral spines. If equal-sized specimens of the two forms 

 are compared, L. furcifer is seen to have wide rounded 

 interbrachial arcs which merge gradually into the ray. 

 Vexator has a smaller disk, never rounded interbrachial 

 arcs, but acute angles, the rays being sometimes swollen 

 at base so that the marginal and adjacent abactinal paxilla; 

 of two rays interlock. L. furcifer reminds one of a five- 

 rayed Solaster, whereas L. vexator suggests a five-rayed 

 Crossaster" . L. vexator again differs from L. furcilliger 

 by its larger disc, thicker arms, more robust actinal as 

 well as marginal paxillae, more robust abactinal spines 

 as well as more closely joined adambulacral plates. 

 Without further entering upon the subject Mortensens 

 remarks in "Conspectus Fauna; Gronlandicae. Echinoder- 

 rner" 4 ) about Fishers forms that these seem to be transi- 

 tion forms from furcifer through vexator to furcilliger, so 

 that these forms can hardly be regarded as more than 

 varieties of furcifer. 



The Bergen Museum possesses very abundant ma- 

 terial of L. furcifer from the Norwegian coast as well as 

 the Norwegian Sea and extreme Arctic regions such as the 

 Kara Sea, Spitsbergen and Jones Sound. This material 

 shows that individuals from the Boreal regions, such as 

 the coast near Bergen, have a pointed interbrachial arc, 

 the arms comparatively narrow at base and tapering 

 gradually toward the point. The individual from the 

 neighbourhood of Bergen figured by Duben and Koren 



!) Bull. Bur. Fisheries, vol. 24, 1905, p. 312. 



2 ) Zool. Anzeiger, vol. 35, 1910, p. 574. 



3 ) Bull. U.S. Nat. Museum, no. 76, 1911, p. 334, tab. 794, figs. 

 1 & 2, tab. 114, fig. 1. tab. 116, tab. 5 and p. 338, tab. 114, tab. 2. 



4 ) Meddel. om Gronland, vol. 23, 1913, p. 336. 



