Il8 NEW YORK STATE MUSEUM 



deltoid [as in fig. 3] or from new centers of stereom formation 

 and therefore homologous with no plates whatever. It is very 

 highly probable that these plates of the fourth circlet are associated 

 with respiration and that there is a regular increase in their number, 

 newer plates being formed at both ends of the row until as many 

 as 20 were formed in each interradius. The remaining plates of 

 the aboral surface and the five single interambulacrals of the oral 

 surface are really indicative of a rather highly specialized type. 



The anal piece, the wing plates, and the brachioles of our genus 

 might perhaps cover an oral surface much like that presented by 

 Asteroblastus and its large number of thecal plates and very remark- 

 able apical piece are suggestive of relationship. Our genus how- 

 ever possesses no diplopores and the remarkable differentiation of 

 the plates of the aboral surface and the unique system of hydrospires 

 clearly separate it from the Protoblastoidea of Bather (1899). The 

 resemblance of the central plates of the oral surface of one to those 

 of the other, seems to be but another example of homoplasy. 



While the deltoids of Codaster offer some remarkable resem- 

 blances to the genus under discussion, we may note that our form 

 still has more than " the normal definite number of plates " ; the 

 hydrospires do not cross over to the radials ; the radials not only 

 are not notched but they are not even in contact with either del- 

 toids or ambulacra, being separated from both by the peculiar 

 large and long bibrachial. The structure of the ambulacrum with 

 its adambulacrals spanning the space between the deltoids, the 

 absence of a lancet ^late, and its peculiar wing plates and anal 

 piece offer characters more than sufficient to separate the form from 

 the Eublastoidea [Bather, 1899]. 



The structure of the ambulacrum on the other hand would at 

 once suggest a position with the Edrioasteroidea as would also the 

 torsion of the oral over the aboral areas of some 7 to 10 degrees 

 toward the right, but the presence of brachioles, not to mention 

 other differences of structure, would exclude it from that group. 



The form seems also to suggest several rather remarkable crinoid 

 affinities. Here we have the marked basal invagination of many 

 forms, the strongly crinoid radials, the group of interbrachials, and 

 at least the suggestion of brachials in the pairs of plates assuming 

 that position. These characters all exist on a differentiated aboral 

 surface and the structure rather closely resembles the crinoid cup. 

 The oral surface is just as extraordinary. Here we have the crinoid 

 tegmen with its five deltoids as in Carabocrinus, its introduced anal 



