26 



ASTEROIDEA. 



lowest beds of the carboniferous rocks ; these beds, Mr. Salter kindly informs me, are called 

 by Mr. Jukes and himself the " Coomhola grits" in Ireland, and which Sedgwick and 

 Murchison called the " Marwood beds" in N. Devon : they are neither Devonian nor Car- 

 boniferous, but lie on the confines of both. This asteroid is not yet described. 



Fig. 16. 



Palasterina, McCoy. 



Palasterina primava, Forbes. Mem. Geol. Surv., decade i, pi. i, fig. 2. 



— — Salter. Ann. and Mag. of Nat. Hist., 2d series, pi. ix, fig. 2, 



from which fig. 16 « is copied. 



Body broad, pentagonal, produced at the angles into five short, lanceolate, or elongato- 



triangular, pointed arms, which are each about two thirds as 

 long as the breadth of the disc. Surface of the disc conyex 

 above {a), as well as the arms tuberculated and reticulated, 

 exhibiting traces of having been covered by tufts of short, 

 blunt spines. Madreporiform plate and vent, both subceu- 

 tral. Beneath, nearly flat ; the inter-ambulacral spaces reti- 

 culated like the upper surface ; the ambulacra composed of 

 broad, oblong, geniculated plates (3), of which there are about 

 twenty in a row. The largest specimens examined had 

 attained the dimensions of an inch and a half in diameter, from 

 arm-tip to arm-tip. This star-fish has many affinities with 

 Asterina or Asteriscus. Mr. Salter has discovered that the 

 " basal or angle ossicula are enlarged, three-cornered, and 

 furnished with a pyramid of spines, pointed inwards. The 

 upper surface is roughly tuberculate, and possesses short tufts 

 of spines." 



Palasterina j)rim(BV a, Forbes, fig. a. 

 „ stellata, Billings, fig. b. 



Locality. — Underbarrow, near Kendal, Westmoreland. 

 It is found in a thin, subcalcareous band of Ludlow Rock, 

 loaded with Trilobites and Encrinites. 



Palasterina antiqua, Hisinger. Leth. Suec, tab. xxvi, fig. 6, p. 89. 



Locality. — Mount Hoburg, Gothland, Sweden ; in Ludlow Rocks. 



The Canadian species of Palasterina I have derived from Dr. Billings' valuable paper 

 on the AsteriadcB of the Lower Silurian Rocks of Canada, in the third decade of Canadian 

 Organic Remains. 



