A very rich and interesting material of echinoderms 

 was collected in the summer of 1910 during the cruise 

 of the "Michael Sars" in the North Atlantic. The material 

 which contained 92 species and 67 genera is distributed, 

 as follows: 



Holothurioidea: 



14 



genera 



21 species 



Asteroidea: 



24 



» i 



30 „ 



Ophiaroidea: 



13 



M 



22 „ 



Echinoidea: 



13 



) J 



15 „ 



Crinoidea : 



3 



1 J 



4 „ 



The greater and most interesting part of the collec- 

 tions was taken from the great depths of the North Atlantic, 

 Peniagone ferruginea, one of the species found 

 there, is new to science, and Peniagone wyvillii taken 

 in the Bay of Biscay by the "Michael Sars" is new to 

 the Atlantic region. It was previously known only from 

 the Pacific. Several of the others are likewise of great 

 interest from a zoogeographical point of view, as their 

 vertical as well as their horizontal distribution has been 

 extended by the explorations of the "Michael Sars". I 

 may thus mention Bathybiaster robustus and Solaster 

 abyssicola which were previously known only from the 

 east coast of North America. The cruise of the "Michael 

 Sars" furnished proofs that they occur also on the east 

 Atlantic side; for Bathybiaster robustus was found west 

 of Ireland (stat. 95) and the Hebrides (stat. 101), and 

 Solaster abyssicola north of the Azores (stat. 88). The 

 northern boundary of Psilasteropsis patagiatus and 

 Astronyx locardi was formerly the Bay of Biscay. The 

 "Michael Sars" found the firstnamed species off the 

 Hebrides (stat. 101) and the latter off Ireland (stat. 95). 

 Benthodytes glutinosa was previously taken only by the 

 "Talisman"in the Sargasso Sea and south of the Azores 

 at depths of 3 175 to 3 432 m. The "Michael Sars" 

 collected the species off the entrance to Gibraltar, 2 603 m. 

 (stat. 35) and besides a very young individual at the 

 intermediary depth of about 1 400 m. southwest of Ireland 

 (stat. 92). Under the description of the various species, 

 however, an account of their horizontal as well as their 

 vertical distribution will be given. 



Only one haul was made in the cold area north of 

 the Faroe-Shetland ridge (stat. 102) where 9 species were 

 taken, all characteristic of the Norwegian Sea. Five of 

 them are found principally in the cold area and occur 

 only exceptionally in the warm and then in the border 

 region only. The other four species on the other hand 

 occur in the cold, as well as in the warm, area, where 

 they have a wide distribution. But they are likewise 

 wanting within the Atlantic region proper. They may 

 perhaps be carried as larvae into the Atlantic by the 

 south-going cold ocean currents across the ridge that 

 divides it from the Norwegian Sea, but they do not 

 settle there. It should be stated that three typical warm 

 water species were also obtained at stat. 102, viz: 

 Plutonaster bifrons, Psilaster andromeda and Zoroaster 

 fulgens, but there is every reason to assume, as I shall 

 show more fully below, that they did not live in the 

 locality, but had accidentally remained clinging to the 

 trawl from the foregoing station (stat. 101), where several 

 specimens of these species were taken. 



The difference between the deep-sea faunas of 

 echinoderms of the Norwegian Sea and the Atlantic 

 appears very distinctly by comparing stat. 101 and 102 

 which lie on either side of the Faroe-Shetland ridge. 

 Neither of the localities gives a complete picture of the 

 echinoderm faunas of the Atlantic and the Norwegian 

 Sea, respectively, as several characteristic species are 

 wanting in the collections from both stations; but 

 the picture is more complete at stat. 101 than at 

 102. At the former 13 species were collected; five of 

 these are known, besides from the Atlantic, also from the 

 banks bounding the Norwegian Sea, the other 8 species 

 on the other hand are restricted to the Atlantic region 

 (I leave out of account here that some of them may 

 also occur in the Pacific and Indian Oceans), but none of 

 them are met with in the cold area of the Norwegian Sea. 



Both regions may have genera in common, thus, to 

 mention a few of them, Bathybiaster, Ophiopleura and 

 Pourtalesia ; but they are represented by different species- 

 Bathybiaster robustus, Ophiopleura aurantiaca and Pour- 

 talesia wandeli occur within the Atlantic region, while 

 Bathybiaster vexillifer, Ophiopleura borealis and Pourta- 

 lesia jeffreysi live in the cold area of the Norwegian Sea. 



