Ophiuroidea — Brittle- stars. 



97 



Starfishes. 



GALLERY 

 VIII. 



East Side. 

 Table- 

 cases 76, 

 76a, & 76, 

 Wall-cases 

 18 & 17. 



series of Palseozoic species from the Lower Devonian of Bunden- 

 bacli, in Germany. An additional set of these is exhibited in 

 a table-case in the middle of the gallery (75a). In this are shown 

 the type-specimens of Stiirtz's monograph on the fauna, pub- 

 lished in 1890 in the ** Palaeontographica." As the fossils of this 

 locality are altered into iron pyrites, they are hard in comparison 

 with the slate in which they are imbedded, and thus they can be 

 cleared from matrix and both sides of the specimen shown. In 

 this collection attention may be especially directed to Palceasteriscus 

 Bevonicus, Cheiroptaster giganteus, and Helimithaster Rhenanus. 



IV. — Ophiukoidea. 

 The Brittle - Stars and Sand - Stars differ from the ordinary 



starfish by having arras sharply marked off from the central disc, Ophiu- 

 roidea— 

 Brittle - 

 stars. 



Wall- case 

 17, Table- 

 case 76. 



Fig. 154.— «, Lapivorthura Miltoni, Salter, sp. Lower Ludlow : Leintwardine, 

 Shropshire. 



b, the under surface of a ray. 



c, the upper surface of a ray with the oral combs. 



t(T which latter the alimentary canal is confined, and by having 

 a series of ossicles forming a kind of backbone running up the 

 central line of the arms. These animals are therefore separated 

 as a distinct class, the Ophiuroidea. The members of this class 

 are of less value to the geologist than those of the Asteroidea, 

 but the collection contains some interesting species. 



One of the best-known forms in the English series is Lapwort/mra 

 MiUoni (Fig. 154), from the Ludlow Shales, in some specimens of 

 which (such as 46,753, and 57,425) the structure of the jaws and 

 the ossicles in the arms can be determined. The genus Eudadia is 

 represented by the type-specimen [Eudadia Johnsoni, H. Woodw.), 

 and has the arms coiled like the recent Euryale. 



