70 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



From this brief summary of the more obvious anatomical features of 

 Heliaster it is clear that the relationship with Asterias is very close, the 

 only important differences being in the number of rays, the degree of 

 their coalescence and the resulting modification of the actinal skeleton 

 and arrangement of pedicels. It will of course be a matter of opinion 

 whether these differences warrant the maintenance of the family Helias- 

 teridae. It seems as though such a course emphasized too strongly the 

 differences between Asterias and Heliaster and tended to conceal their 

 much more important resemblances, and while the Heliasters might be 

 considered a sub-family (Heliasterinae) of the Asteriidae, it would be un- 

 wise to isolate them further. If this sub-family be recognized, it is pos- 

 sible that the two Heliasters with relatively few, long, free rays (inultira- 

 diatus and kubiniji) could be separated generically from the others. It 

 is difficult to do this, however, on account of the intermediate characters 

 shown by canopus, which has few, rather long, and quite free rays, but 

 whose natural relationship is obviously with heliantlius. Should we 

 make a second genus of these two species, leaving cumingii, polybrachius, 

 and microbrachius for a third, we should doubtless have a natural group- 

 ing of the species, but the definition of these "genera" would tax the 

 keenest specialist, and it is difficult to see any real advantage from such 

 a division. It is, moreover, quite possible that when these starfishes are 

 studied as living organisms (instead of as museum specimens), and from 

 a more extensive series of localities, our idea of their interrelationships 

 may be considerably changed. 



Granting, then, that Heliaster is to be accepted as a genus of Asteri- 

 idae, we may well inquire as to its relation to other genera of that family, 

 and we naturally turn to Pycnopodia as a probable near-ally, on account 

 of the large number of rays. That Heliaster is allied to Pycnopodia has 

 recently been both assumed and affirmed by Kitter and Crocker (1900). 

 They make the following statement in a footnote on page 249 : — " There 

 appears to be general agreement among authorities that Pycnopodia and 

 Heliaster are rather *more closely related than are Heliaster and Labidi- 

 aster. A. Agassiz, '77 ; Perrier, '93 ; Ludwig, '97 ; Studer, '84 ; Vignier, 

 '78, etc." (both in this place and on p. 270, Yiguier's name is mis- 

 spelled, by a common typographical substitution). As my own inves- 

 tigations had led me to a different conclusion, I looked up the references 

 here given, making use of course of Ritter's and Crocker's bibliography, 

 with the following remarkable result : — 



