REPORT OF THE DIRECTOR I915 II9 



sea stars, which will necessitate the formation of a new subclass of 

 Asterozoa. Spencer in 1914, page 47, says, " In fact, careful 

 analysis discovers that the true Asteroidea were represented in 

 early Palaeozoic times by but few genera and species." Again, on 

 page 52, he says, " The number of divergent branches of the 

 Asterozoan stock can not be expressed by the present dual division 

 into Asteroidea and Ophiuroidea — a classification which, it must 

 be remembered, is merely based on knowledge of the recent sur- 

 vivors of many ages of experiment and trial." 



While writing my description of Protopaleaster nar- 

 r a w a y i I had before me the types of Urasterella pul- 

 c hell a (Billings) and Stenaster salteri, Billings. An 

 examination of a portion of a food groove of U. pulchella, 

 to reveal the exact location of the supposed necessary podial open- 

 ings, demonstrated the fact that such pores were not present where 

 we find them in Asteroidea. There remained only the possibility, 

 suggested by the relaxed condition of certain arms such as that 

 shown in plate 11, figure 2, that the podial openings formed a single 

 medial series, a conclusion apparently verified by my belief that in 

 Protopalaeaster narrawayi I was viewing the oral 

 surface of the specimen. 



Here then appeared to be a new type of food groove and one 

 apparently also shown by Palaeaster niagarensis Hall, 

 and Mesopalaeaster (?) parviusculus (Billings) . 

 True ambulacra appeared to be absent and therefore in my defini- 

 tion of the new order Eostelleroidae (1912, page 5) I used the term 

 adambulacra as synonymous with floor plates where ambulacrals 

 were believed to be lacking. The form, in my definition, requiring 

 the double row^ of podial openings was Stenaster salteri, 

 which seemed to show but one double row of plates inside true 

 marginals. Had I excavated but a single one of these apparent 

 podial openings I should have been forced to the conclusion that' 

 here at least was a form absolutely without such structures. 

 Spencer's studies of hundreds of specimens had already led him to 

 the belief that none of the oldest fossil sea-stars had developed 

 podial openings. Had I possessed his grasp of these older con- 

 ditions, the fact that P . n a r r a w a 3M showed a medial line of 

 pores would have been uSed as evidence that the plates between 

 which they passed could not be floor plates. Of course, the most 

 conclusive evidence as to whether I mistook the apical for an oral 

 aspect in my description must come from the additional evidence 



