1882.] 



THE STRAITS OF MAGELLAN. 



651 



other hand, there is no such interspace, in consequence of the 

 different form of the basal joints, while the distal edge of the 

 succeeding joints is provided with a delicate spinous process, which 

 appears to be absent from the northern form. The accompanying 

 drawings represent the second pinnules of A. eschrichti (A), and its 

 variety (B). 



A difference of this kind can hardly be taken to be specific, 

 though, of course, there is a " personal equation " in zoology which 

 renders it within the bounds of possibility that some brother natu- 

 ralist may look upon it as having a higher distinguishing value than 

 I am inclined to ascribe to it. Morphologically, the forms appear 

 to belong to the same species ; and the differences are best marked, 

 in the language of systematic zoology, by speaking of the new Cri- 

 noid as Antedon eschrichti, var. magellanica. 



It is not for the first time that attention has been directed to a 

 resemblance between an arctic and an antarctic form ; but never, 

 perhaps, has the resemblance been so difficult of explanation. For 

 myself, I feel compelled to confess that by no effort of the imagina- 

 tion can I figure to myself the passage of this fixed form over so wide 

 a tract of sea and coast. If such has taken place, it will have to 

 be allowed that the larva can hardly be free for so short a time as 

 is the case with the best-known British species. Nor can it be well 



