328 Mr. J. W. Salter on some new Palceozoic Star -fishes. 



[If Pter aster militaris, Miill., be compared with our fossils, it 

 will be seen that the inner row of plates bordering the avenues 

 is very large, but bears a comb of spines comparable to that on 

 the outer row of Palceocoma. For the accompanying figures I am 

 indebted to the kindness of Mr. L. Barrett. 



Fig. 1. Fig. 2. 



Fig. 1. Pter aster militaris ; part of reticulated upper surface. 

 Fig. 2. Ditto, inferior plates, with combs of spines : a, ambulacral space ; 

 b, adambulacral row of plates ; c, outer series.} 



The first discovered and most plentiful species of Palaocoma 

 is the 



1. P. Marstoni, n. sp. PL IX. fig. 3. 



P. triuncialis, brachiis lanceolatis, quam latis quadruple longioribus, 

 apicibus obtusis ; ambulacris angustis ; spinis brachiorum mar- 

 ginalibus rigidis baud longis ; ore magno. 



Shorter spines, set at a wide angle from the margins of the 

 arms, distinguish this from the next species. The beautiful and 

 delicate web-like disk between the arms bears short spines also ; 

 it is sometimes expanded as in our figure, but more generally 

 contracted, so as only to make the arm a little broader, and give 

 it a blunt appearance. The mouth is wide, of a true pentagonal 

 shape, and with rather strong bordering plates, of which the tri- 

 angular adambulacral plates (*) in fig. 3, 5, are most conspicuous. 

 The stellate calcareous spiculse which dot over the thin disk are 

 easily seen through the opening of the mouth. 



Dedicated to my young friend Mr. Alfred Marston of Ludlow, 

 to whose kindness I owe much valuable information, and the 

 free use of all his choicest specimens. He is an ardent collector 

 of the fossils of his district, and well acquainted with their 

 characters. 



Loc. Church Hill, Leintwardine. (Lower Ludlow.) 



2. P. Colvini, n. sp. 



P. planus, sesquiuncialis, spinis longissimis flexuosis hirsutus ; bra- 

 chiis ligulatis et cum disco tenui spinosissimis ; ambulacris angus- 

 tis ; ore parvo. 



Col. Colvin, C.B., of Leintwardine, found the first specimen 

 of this remarkable star-fish, which in the length of its hair-like 



