740 RECORD OF CURRENT RESEARCHES RELATING TO 



its range, botli geographical and bathymetrical. It is almost exclu- 

 sively a tropical genus, its northern limit being about 30° N. lat. and 

 its southern 40° S. lat. Isolated species are known from the Cape of 

 Good Hope, Natal, South Australia, and Port Jackson, but its chief 

 home is Oceania, especially the Philippines. A few Actinometra 

 species are also known from the west coast of the Atlantic, as South 

 Carolina, the West Indies, Bahia, and St. Paul's Kocks. 



The bathymetrical limit of Actinometra is likewise very slight. 

 Nearly all the' Challenger ' species are from depths less than 20 fathoms, 

 while only three come from a greater depth than 100 fathoms. The 

 individual species of Actinometra, like the genus itself, are very local 

 in their distribution. Each of the forty-eight species of the ' Challenger ' 

 collection has its own locality. 



With Antcdon, however, the case is different. Not only do nearly 

 all the deep-sea Comatulce belong to this genus, but some species of it 

 have a fairly wide range. Ant. rosacea ranges from the north of 

 Scotland to the Mediterranean, while Ant. Eschrichtii is found over a 

 much wider area. It is well known on the American coast, and was 

 dredged by the 'Challenger' oif Halifax, while the 'Porcupine' met 

 with it in the " cold area " of the North Atlantic. 



Some Antedon species occur in duplicate from different localities. 

 Two species from near the Kermadec Islands (S. 170), also occur in 

 the neighbourhood of the Fijis (S. 174, 175). A third species was 

 dredged at Stations 147 and 160, two localities in the Southern Sea, 

 in nearly the same latitude, but separated by almost 90° of longitude. 

 A fourth species came up from 1070 and 775 fathoms, off the Admiralty 

 Islands and Japan respectively. 



The above facts would seem to show that, with few exceptions, the 

 geographical range of the individual members of the family Comatulidce 

 is exceedingly limited, nearly every species having its own locality, 

 and that not a very extensive one. 



The voyage of the ' Challenger ' has settled a curious question in 

 connection with the Criuoids, the origin of which is due to Loven. It 

 refers to Hijponome Sarsii, a so-called recent Cystid, which turns out 

 to bo notliing more than the disk of a Comatula, minus its skeleton. 

 The antambulacral plating may be very extensive,''forming a complete 

 pavement over the ventral surface of the disk as in many Pentacrini ; 

 and the ambulacra are not wide and open as is usual in most Comatulce, 

 but almost entirely closed by the approximation of the marginal leaf- 

 lets at their sides, so that the food-grooves radiating from the mouth 

 are converted into tunnels. 



The plates in the marginal leaflets are probably movable as un- 

 plated leaflets are in Antedon rosacea; so that they can be erected 

 when the arms are spread out, leaving the grooves open for food 

 particles to travel towards the mouth. On the other hand, when the 

 arms are all contracted over the disk, the marginal plates fold over 

 the grooves and cover them in. This is the condition of most spirit- 

 specimens, but it is not in any way comparable to that of the Palfeozoic 

 Crinoids, in which the mouth is truly subtegminal while the ambulacra 

 become real tunnels beneath the upper siu'faco of the vault. 



