ATLANT. DEEP-SEA EXPED. 1910, VOL. HI) 



ECHINODERMATA 



15 



spinelets" 1 ). He must have been aware then that the 



number of papillae may vary. Some adambulacral plates 

 of the "Michael Sars" specimen have 7 furrow-papillae like 

 PL intermedins, others 8 and again others 9 as in the spec- 

 imen described by Sladen. The number given in Verrill's 

 diagnosis is „about seven or eight . . . spines", which 

 likewise shows that the number of papillae may vary. 

 Moreover the arrangement of the secondary papillae is 

 subject to variation as shown by the specimen under 

 discussion. PL intermedins can therefore not be con- 

 sidered as a distinct species, but only as a variety of 

 PL agassizi. 



Plutonaster agassizi was first taken off the east coast 

 of North America, where it was found by several Ame- 

 rican expeditions and by the "Challenger" at several 

 localities between 35° 45' and 41° 53' N, 333—3111 ra- 

 it was later on taken by the "Blake" off the Antilles, 24° 

 24'— 24° 36' N, 1524—1748 m, and by the "Michael Sars" 

 south of New-Foundland. The Prince of Monaco took it 

 off Madeira and the Azores and in the Bay of Biscay, 

 1165 — 1900 m. On the west Atlantic side it is distributed 

 from 24° 24' to 42° 59' N, and on the east Atlantic side 

 from 32° 39' to 43° 33' N. The bathymetrical distribution 

 is 333—3111 m. 



Dytaster agassizi Ed. Perrier. 



Dytaster agassizi Ed. Perrier, Echinodermes, Exp. Sci. du ..Trav.iilleur" 

 et du ..Talisman", 1894, p. 302, tab. 19, fig. 2. 

 18 /t. Stat. 88, 45° 26' N., 25" 45' W., 3120 m., sand and yellow 

 mud, temp. 2.5° Cel. 34 specimens. 



The smallest specimen measured: arm-radius 29 mm. 

 disc-radius 6.5 mm., the largest 61 mm. and 12 mm. 

 respectively, r : R is thus in these specimens 1 : 4.46 and 

 1 : 5.08. This proportion varied, however, between 1 : 4.46 

 and 1 :5.65 in 15 specimens. In the two smallest speci- 

 mens only was R <c 5r. I Perriers type specimen, which 

 was a little larger than the largest of my specimens, the 

 proportion was R = 5.15 r. 



The ventro-marginal plates commonly bear one large 

 spine, but they may have two, particulary in the angle 

 of the arm, and more rarely three larger spines or one 

 large and one or two smaller spines. The dorso-marginal 

 plates bear one spine, but as an exception those in the 

 arm-angle may have two smaller spines. The ventro- 

 marginal as well as dorso-marginal plates may, however, 

 be without spines, especially in the outer half of the 

 arms. 



The mouth-plates have 10 — 11 papillae along the 

 inner free margin. The adjoining adambulacral plate 

 has 8 papillae, the remainder 7 — 10, in the outer half of 



the arm not more than 6—8. Besides the furrow-papillae 

 two more rows of adambulacral papillae were found with 

 4 — 5 papillae in each row, the outermost of which was 

 usually very indistinct, however, and its papillae tiny. 



According to Perrier the actinal areas of Dytaster 

 agassizi are furnished with numerous pedicellariae, of which 

 he remarks: "une trentaine des ces pedicellaires couvrent 

 presque l'aire interambulacraire ventrale, les autres sont 

 disposes isolement le long de la gouttiere ambulacraire 

 comme les plaques dont ils dependent". The specimens 

 examined by me have not such a great number of 

 pedicellariae, nor were they grouped in the manner descri- 

 bed by Perrier. The number of pedicellariae appears to 

 be subject to great variations, however. In some speci- 

 mens a few pedicellariae only were found in each actinal 

 area and there were even areas in which the pedicellariae 

 were entirely wanting. No specimens had more than 

 about 20 pedicellariae in each area, and they exhibited 

 no grouped arrangement, but were scattered among the 

 spines of the actinal plates. In spite of this difference 

 I have referred the specimens to Dytaster agassizi Perrier 

 as they agree with it in other characteristics. Thus the 

 mouth- and adambulacral plates have the same armature, 

 the actinal area has the same extension as in the 

 specimens in questions, the 4th ventro-marginal is tangent 

 to the 5th adambulacral plate, etc. 



The colour in life is red. 



Dytaster agassizi was first taken by the "Talisman" 

 between Europe and the Azores, 4060 m. It was again 

 found there by the Prince of Monaco in two localities, 

 4020—4360 m. According to the explorations of the 

 "Michael Sars" its horizontal distribution will be from 

 38° 8' to 45° 26' N., and from 17° 58' to 25° 45' 

 W. The bathymetrical distribution ranges 3120 to 4360 m. 



Astropecten irregularis Pennant. 



Asterias irregularis Pennant, British Zoology, vol. 4, 1777, p. 52. 



Vi. Stat. 1, 49° 27' N., 8° 36' W., 146 m„ fine sand, temp. 

 9.57° Cel. One specimen which measured: arm-radius 32 mm, disc- 

 radius 8 mm., 28 dorso-marginal plates. 



!%. Stat. 3, 49° 32' N., 10° 49' W., 184 m., fine sand, temp. 

 10.3° Cel. Three specimens measured: arm-radius 37 — 39 mm, disc- 

 radius 9 — 12 mm, 27 — 29 dorso-marginal plates. 



Astrospecten irregularis is an East-Atlantic species, 

 ranging from the Josephine Bank (36° 41') to the Lofoten 

 Is. (68° 20'). It is besides recorded from Tromsoe 

 (Danielssen) 1 ) and the Barents Sea (Hoffmann) 2 ). I am, 

 however, inclined to consider their records as based on 

 misidentifications of Leptopty 'chaster arcticus as Astro- 



') Sladen: Challenger Asteroidea, p. 91. 



'). Kgl. norske Vidensk. Selsk. Skrifter, bd. 4, h. 2. 1859, p. 159. 

 2). Niederland. Archiv f. Zool., Suppl. Bd. 1, 1882, p. 9. 



