I 



PENNATULA PHOSPHOREA. 47 



number of small spicules. Zooids situated aloiif,' the wliole ventral 

 surface of the rachis, and also on the lateral surfaces between the 

 leaves. Polypes in cups, beset with calcareous spicules ; calyx 

 processes variable in uumber." 



Kolliker distinguishes four species of l'i>iinntid<i, whose leading 

 characters are as follow : — r 



1. I'eniHitula phoi>j)horea . Leaves formed of single rows of polypes, 

 eight to eighteen in number, eight calyx processes to eacli polype ; 

 reproductive organs contained in the leaves. 



2. Pfiiniitulii nthni. Leaves formed of single rows of polypes, 

 twenty-five to forty-six in number, placed alternately, so as to give the 

 appearance of double rows. Calyx processes usually three or four to 

 each polype ; reproductive organs confined to the parts of the leaves 

 within the rachis. 



3. Peniuitula borealis. Large pens, up to thirty-two inches long 

 leaves thick, formed of two to four rows of polypes. 



4. Pciniatithi fimhriata. Leaves formed of two rows of polypes. 



Of Pi'iinatula pho^phoreo, to which the Oban specimens clearly 

 belong, three chief varieties are mentioned by Kolliker : — 



a. P. phosphorea, var. anciiisti folio. Leaves long and narrow ; polype 

 heads few in number, and wide apart. 



b. P. pho'^phorea, var. InncifoUd. Leaves lanceolate ; polype heads 

 numerous and placed close together. Of this variety, to which the 

 Oban specimens are to be refen-ed. Kolliker distingi;ishes four sub- 

 varieties. 



c. P. phosphorea. var. aculeata. Leaves narrow and some distance 

 apart ; on ventral side of rachis are four to six rows of prominent spines 

 connected with the zooids. 



1.— Habits.— 



1. The Natural Position of Pennatula. — On this point the various 

 zoologists who have described Pennatula from living specimens differ 

 remarkably. 



Ellis,* speaking of Pennatula, says : — " This genus of animals diffei's 

 remarkablj' from all the other Zoophytes by their swimming freely 

 about in the sea, and many of them having a muscular 

 motion as they swim along. I know of none of them 

 that fix themselves by their base, notwithstanding what has 

 been wrote." Other anatomists have described Pennatula as having 

 the power of swimming freely, and Dr. Grant goes so far as to say 

 that " a more singular and beautiful spectacle could scarcely be 

 conceived than that of a deep purple P. phosphorea, with all its delicate 

 transparent polypi expanded and emitting their usual brilliant 

 phosphorescent light, sailing through the still and dark abyss by the 

 regular and synchronous pulsations of the minute fringed arms of the 

 whole polypi." 



Ellis and Solander, Natural History of Zoophytes, 178G, p. 60. 



