Silurian.} ' PALvEOXTOLOGY OF VICTORIA. lAsleria. 



Plate X., Fig. 1. 



PETE ASTER SMYTHI (McCoy). 



[Genus PETE ASTER (Billings). (Class Echiuodermata. Order Asteri*. Fam. Uras- 

 teridje.) 



Ge?i. CAar.— Stellate of 5 rays, moderately tapering, haying on each side of the ambulacral 

 groove 1 row of adambulacral plates, 1 row of marginal plates, and a few smaller disc plates, 

 extending a variable distance along the rays.] 



Description. — Five broad senii-plliptical lobes meeting' at slig-htly rounded 

 re-entering- angles, leaving- the length and the width at base of the rays nearly equal 

 and le.'ss than the width of the disc. The upper surface is covered with crowded 

 irregularly polygonal tumid plates. Madri'poriform tubercle very large (IJ lines 

 in diameter), irreg-ularly porous, and rug-g-ed with branching- vermicular ridg-es, 

 escentric towards base of the two posterior rays. Ambulacral g-roove very narrow, 

 bordered with a row of laig-e transversely oblong- adambulacral plates, wider than 

 long-, about 6 in 2 lines at middle of ray ; margin of the rays bordered with a rather 

 smaller row of similar marginal plates; between the row of adambulacral and 

 marg-inal plates an intercallary row of small irregular plates. Width of disc between 

 the rays, 7 lines ; from tip to tip of rays, about 1 inch 2 lines; length of ray, about 

 5^ lines. 



This very remarkable starfish has clearly the intercallary row of 

 plates Ijetweeu the marginal and adambulacral rows of plates 

 distinguishing Petraster from Palceaster. 1 dedicate the species to 

 Mr. R. Brough Smyth, who discovered it, and kindly gave me the 

 specimen figured several years ago for the Pulilic Museum 

 collection. From some accident of decomposition, one part of the 

 specunen figured shows the skin of the dorsal surfixce with its 

 irregular plates and madreporiform tubercle, while two of the 

 rays show the plates of the lower surface. 



Very rare in the fine sandy U])per Silurian rocks of Moouee 

 Ponds, Flemingtou, a little north of Melbourne. 



A smaller specimen found since the above figures and description 

 were made, having the rays scarcely 3 lines long from the re- 

 entering angle at base to the apex, has nearly 9 adambulacral 

 plates in the space of 2 lines. This si^ecimen shows the ellipticalh' 

 pointed end of the rays, with the rows of adambulacral, marginal, 

 and intercallary, plates distinctly. 



EXI'LANATION" OF FiGrEES. 



Plate X. — Fig. 1, partly dorsal and partly ventral view, natural size. Fig, In, do., mag- 

 nified. Fig. \h, one of the plates magnified to show the granular surface. 



[ 41 ] F 



