REVISION OF PALEOZOIC STELLEROIDEA. Ill 



cinnati, Ohio. It is now in the Dyer colloction, j\Iuseum of Com- 

 parative Zoology (No. 22), Harvard University. The original of 

 Astcrias antiquata Locke was found at Cincinnati, but the specimen 

 appears to be lost. 



Remarks. — Meek (1873) in describing this specimen, provisionally 

 referred it to Palseaster granulosus Hall and commented as follows: 



"Although this fine Star-fish agrees pretty well in most of its 

 characters with the description of Palxaster granulosus of Hall (wliich 

 has not yet been figured) , I am far from being entirely satisfied that it 

 is really the same, as it seems to differ in some important respects. 

 For instance, the rays of P. granulosus are described as being 'obtusely 

 rounded at the extremities'; while in the form under consideration 

 they are rather acutely rounded, if not angular. Again, instead of 

 having 25 of the marginal pieces on each side, in a space of one inch 

 and a quarter from the apex of each ray, and 42 or 43 of the adam- 

 bulacral, it shows in this space 28 marginal and only 32 adambula- 

 crai pieces. The number of the latter being about 10 less on each 

 side in the same space — a rather decided difference, showing the 

 inner row to consist of proportionally larger pieces. Its ambulacra! 

 ossicula seem to have the same proportional breadth and length as in 

 the type of P. granulosus and also have each a similar ridge across 

 the middle; but these ridges do not show the zigzag arrangement 

 mentioned in the description of P. granulosus. Prof. Hall does not 

 say how many rows of pieces are seen on the dorsal sides of the rays 

 of his species; but he states that it is probably the same species that 

 the Western Academy of Sciences sent out lithographs of under 

 the name Astenas primordialis. One of these lithographs, now 

 before me [reproduced here on plate 14, figs. 1, 2], represents from 

 8 to 10 rows of these dorsal pieces, wliich is 6 or 8 less than may be 

 counted near the middle of the rays of our specimen. 



**In noticing this form in the Am. Jour. Sci., vol. 3 (3d series), 

 p. 277, I proposed, in case it should be distinct from P. granulosus, 

 to call it P. speciosus." 



With such marked differences between P. granulosus and P. speci- 

 osus, and since the typo-specimen of the former can not be located 

 to determine the interbrachial structure, it is deemed advisable to 

 adopt Meek's name P. speciosus for the specimen described above. 



In the upper portion of the Ordovicic in the Richmond formation 

 occurs another closely related species, P. heJlulus, which is dis- 

 tinguished from P. speciosus in having more slender rays and usually 

 a greater number of plates in the actinal columns. The greatest 

 difference, however, is that it has seven pairs of adjoining adam- 

 bulacral plates proximal to the interbrachial plates, while in P. 

 speciosus there are but two or three pairs of adambulacrals. In 

 other words, the adambulacral oral extensions are far longer in 

 P. hellulus than in P. speciosus. 



50601°— Bull. 88 — 15 8 



