REVISION OF PALEOZOIC STELLEROIDEA. 203 



cord, as seen from below ; farther out these become the marginal pieces 

 of the free rays. There is ; however, no regular row of marginal 

 pieces to the disk between the rays. [In other words, there are no 

 infra- or supramarginals.] Oral pieces ten, anchylosed ( ?) in pairs, so 

 as to look like five pieces merely emarginate at the outer and inner 

 ends. (Other characters unknown.) 



"Of course it is not possible to give a systematic diagnosis of a 

 genus like this, of which only imperfect fossil species are known. 

 All that can be done, in cases of this kind, is to give such of the more 

 prominent characters as happen to be visible in the particular speci- 

 mens accessible; while we can not always be sure, until better speci- 

 mens are obtained, and other species known, whether some of the 

 characters given may not be merely specific, or in other cases of 

 more than generic importance. At the same time, we have to regret 

 our inability to give any information in regard to some of the more 

 delicate parts that would be the first to claim the attention of the 

 zoologist in describing existing starfishes. 



"In first publishing a description of the beautiful species forming 

 the type of this genus, we referred it provisionally to McCoy's genus 

 Palasterina, under the subgeneric name Schcenaster. Later com- 

 parisons, however, have satisfied us that it can not properly be retained 

 in that genus; and as it seems to present equally important differ- 

 ences from all the other established genera known to us, we now 

 propose to separate it as a distinct genus, under the name Schoenaster. 

 It is probably most nearly allied to the Silurian genus, Palasterina, 

 but differs in the peculiar oblique, outward, imbricating character 

 of its row of plates on each side of the ambulacral furrows, and the 

 distinct inward imbricating character of the minute, scale-like plates 

 covering the under side of the disk. There are likewise differences 

 in the arrangements of the plates and pores of the dorsal side of the 

 free arms, as seen in our figure 7&, pi. 19. 



"As the disk is not seen in the specimen from which figure 7d, 

 of the plate just alluded to, was drawn, it presents so different an 

 appearance from fig. 7a of the same plate, showing the upper side 

 of the fossil, that, looking at these figures alone, doubts might arise 

 whether or not they belong to the same type. An examination, 

 however, of the upper side of the same specimen from which 7d was 

 drawn, as well as of other fragments, shows them to be the same. A 

 fragment of the same specimen from which fig. Id was drawn also 

 shows portions of the under side of the disk. 



"Another species, apparently of this genus, from the Burlington 

 limestone, with much narrower ambulacral furrows 1 , shows numerous 



i "We should explain here, that the ambulacral furrow of the enlarged ray, represented by fig. 7c of 

 plate 19, is proportionally too broad, in consequence of the accidental flattening of the specimen, and in 

 part to the adambulacral pieces being represented proportionally too small. These furrows are more 

 nearly natural in fig. 7d, but even in that specimen they are proportionally wider than in undistorted 

 examples." 



