110 BRITISH PALAEOZOIC ASTEROZOA. 



side of tlio marginalia and does not separate them. The distal intermarginal is a 

 small triangular plate in an angle between two supero-marginalia. A few small 

 apical plates may be seen in the axils of the arms, but there is no conspicuous 

 interbrachial area. 



Apical Surf are (Text-fig. 70). — The figure given is a plan of the ossicles of the 

 apical surface of arm iv. It will be noticed that the restoration does not include 

 much of the disc region. I was unable to clear this region, as the fossil showed 

 that it might break up. The portion of the arm exposed is very like that of 

 " Kudsonaster." There is a row of stout radialia bordered on each side by supero- 

 marginalia. The latter ossicles are alternate with the radialia in the proximal 

 portion of the arm and come to lie opposite to them in the distal region. A few 

 small adradialia enter the base of the arm just as they do in the early Mesopalae- 

 asterinee (see p. 78). A suggestion that the form is reaching an advanced lineage 

 stage is conveyed by the pronounced lack of symmetry of the proximal supero- 

 marginalia, that on the left side being stout while that on the right is broken up 

 into smaller ossicles. The under-surface of one of the disc-plates lies partially 

 exposed in the interradius between arms iv and v. Its appearance is almost exactly 

 similar to that of the under-side of one of the disc ossicles of Calliasterella mira, 

 Trautschold, figured by Schondorf (65, pi. xxiv, fig. lb). 



The ornament on the radialia and supero-marginalia is pustular like that on the 

 infero-marginalia. 



Measurements. — R : r : : 24 mm. : 7 mm. Width of arm at base is 8 mm. 



Horizon and Locality. — Middle Silurian (Wenlock Limestone) of Dudley, 

 Worcestershire. 



Genus LEPIDASTER, Forbes. 



1850. Lepidatter, Forbes, British Organic Remains (Mem. Geol. Surv.), dec. iii, p. 1. 



Generic Characters. — Multiradiate. Proximal adambulacralia profoundly modi- 

 fied. Marginalia and the apical plates tend to lose their differentiation and to 

 resemble each other. 



1. Lepidaster grayi, Forbes. Plate VI, fig. 6; Plate VII, figs. 1 — 6; Text-figs. 



71-78. 



1850. Lepidaster grayi, Forbes, British Organic Remains (Mem. Geol. Surv.), dec. iii, p. 1, pi. i, 



figs. 1-3. 

 1862. „ Wrigbt, British Foss. Echinodermata, Oolitic, vol. ii (Palseont. Soc. for 1861), p. 35. 



? 1873. Trichotaster plumiformis, Wright, Quart. Jouru. Geol. Soc, vol. xxix, p. 421. 

 1874. Lepidaster grayi, H. Woodward, Geol. Mag., dec. ii, vol. i, p. 9. 

 1879. „ grayi, Zittel, Handb. Palseont., vol. i, p. 454. 



1890, ,, grayi, Stiirtz, Palseontographica, vol. xxxvi, p. 222, pi. xxviii, figs. 19-20. 



