PENNATULIDA. 91 



depths, will certainly be found distributed over the greater part of the widely-extended depths of the 

 Atlantic, as far as the positive bottom-temperatures are found. 



With regard to the bathy metrical range, the species treated off here show the peculiar 

 feature that most of them may occur at very different depths; many of them have a surprisingly great 

 vertical range. In the following list the least and the greatest depth at which each species has 

 hitherto been found, is given as far as possible. 



Fathoms 



Pennatula phosphor ea 5-10114 



aculeata 30-1255 



prolifcra 11991435 



grandis 501255 



Virgularia affinis 60100 



mirabilis 5 200 



cladiscus 40 555 



Stylatula (Diibenia) elegans 30 550 



Pavonana finmarchica 60980 



Halipteris christii c. 200 



Protoptilum thomsoni 150 440 



Fathoms 



Protoptilum carpenteri 690 1700 : ) 



denticulatum 1695 



Funiciilina quadrangularis 10 1135 



Distichoptilum gracilc 7001245 2 ) 



Kophobelcmnon stelliferum .... 20 over 2000 (2369) 



Bathyptilum carpenteri ! , 650 



Anthoplilum grandiflorurri f> l' J /: :^.\ R . :i'. . 1311106 



,. ., 



nntrrayn 640 1362 



Umbellula lindahli '.'. XH 1 .?^. 1 . .*?: 122 14353) 

 encrinus . . '?. .?J. '^!'.. '. c. 105-762 



I SSI^ II V 



According to this list only four specimens would seem to be exclusively deep-sea forms: Pen- 

 natula prolifera, Anthoptilum murrayi, Distichoptilum gracile, and Protoptilum denticulatum] as only 

 one specimen of the latter has been taken, however, I think it better to make a reservation with 

 regard to it. Several of the species which are known to reach to very great depths, seem, however, 

 to have their natural home in somewhat higher regions: Pennatula aculeata occurs most frequently 

 between 150 and 300 fathoms; Pcnn. grandis, Funiculina quadrangularis, Halipteris christii, Pavonaria 

 finmarchica, Anthoptihtm grandiflorum, Kophobelemnon stelliferum, Protoptilum thomsoni, Umbellula 

 encrinus, perhaps still more, seem to occur in greatest numbers and to be largest and most developed 

 in similar small and moderately great depths. With regard to these and several other sea-pens the spe- 

 cimens taken at very great depths are only young stages; even if they are provided with sexual 

 organs, sometimes even with ripe sexual products, their outer form has either not reached full 

 development, or may even be so little developed, that in several instances these specimens have been 

 interpreted as independent species or genera of simple structure. From this fact originates the view 

 advanced by Kolliker (Monogr. p. 449 and Chall. Report p. 39), that it is upon the whole the simple 

 forms of Pennatulids which live in the great depths, whilst the more complicated* or differentiated 

 forms belong to less deep waters ; and since the forms interpreted as primitive > ones are as usual regarded 

 as the oldest, he has also thought he found the supposition corroborated in the distribution of the 

 Pennatulids, that the remainder of an otherwise extinct, ancient fauna was living in the great depths. 

 This latter supposition is upon the whole not very probable ; I shall not, however, treat of this question 



') Verrill states that he has found it at less depths, comp p. 54; but he gives no depth. 



2) In the Pacific 8851573 fathoms. 



3) U. bairdi, which is presumably the same species, reaches to 2033 fathoms. 



