332 Mr. J. W. Salter on some new Palaozoic Star-fishes. 



character for distinguishing the species ; they are scarcely half 

 the width of the outer plates. 



Named in compliment to our friend R. Lightbody, Esq., of 

 Ludlow, an indefatigable collector and liberal donor. 



From the same locality as the last. 



3. P. Sedffwicki, Forbes. 



P. SedgwicJci, Forbes in Mem. Geol. Surv. Decade 1. pi. 4. 



P. disco conspicuo, brachiis elongatis, superne ossiculis quadratis, 

 alternatis, profunda exaratis, infra ambulacro latissimo, ossiculis 

 convexis ; spinis ? ; ore rosaceo. 



The disk in this species is large, full J of an inch in breadth, 

 and coarsely reticular. The arms start nearly from the centre, 

 leaving a small five-petaled rosette, which corresponds to the 

 oral pentagon below. The rays are rather broad, and very 

 strongly sculptured, convex along the middle line, as in P. lep- 

 tosofua, with a sharp median line and short sutural grooves. 

 The outer half is far more deeply grooved than in the preceding 

 species, the strong, oblique furrow occupying nearly all the cen- 

 tral portion of each ossicle, and leaving a thickened margin all 

 round. The ossicles are transverse, nearly twice as wide as long, 

 and show no trace of spines in the figured specimen (a cast of 

 which I have before me), though such are represented by Forbes 

 in his restored figure, having probably been detected in other 

 specimens. 



On the under side the arms present a good character in the 

 very wide and convex median (ambulacral) rows, much wider 

 than in P. Miltoni or the P. leptosoma, and even wider than the 

 lateral plates. The central pentagon is very deeply cut, of five 

 oval, pointed petals. 



Loc, Underbarrow, Westmoreland. 



4. Another species of this genus, P. Salteri *, should be sought 

 for by collectors in the Lower Silurian rocks, near Cerrig-y- 

 Druidion on the Holyhead Road. Prof. Sedgwick and myself 

 found a very perfect specimen in the large quarry there, but it 

 was unfortunately lost by the late Prof. Forbes. 



PALiEODISCUS, n. g. 



It now only remains to notice the somewhat anomalous form 

 to which the above name seems appropriate, and which, whether 

 it eventually prove to be an incomplete specimen or not, difiers 



* Quart. Geol. Journal, vol. i. 1846, p. 20. 



