CARACTACASTER CARACTACI. 



83 



and are succeeded by tlie normal succession of adambulacralia. The condition 

 of preservation of the plates, however, does not allow of complete description. 

 I have restored the mouth-angle plates as if they were originally thin and 

 triangular. Only the base of the plates, however, is preserved, with rather 

 indistinct traces of their continuations into the mouth-cavity. The adambulacralia 

 do not completely hide the groove, and the ambulacralia are consequently exposed. 

 Fortunately, the British Museum specimen possesses ambulacralia still preserved 

 in the original calcite. One or two of these plates came away from the specimen 

 when I was making casts. These were distinctly oblong, with the usual ridge. 



43 



42 



Text-fig. 42 (on left). — Plan of portion of disc and the base of au arm of CaractacaHer caractaci ? 



(based on E. 13531). x 12. 

 Tkxt-fig. 43 (on right). — Plan of the apical surface of the base of an arm of Carat- tacaster caractaci 



(based on E. 13531). x 12. 



Measurements. — 



4/30. r is 4 mm. Width of arm at base is 5"1 mm. 



4/30fl. li : r : : 18"1 mm. : 4'8 mm. Width of arm at base is G mm. 



4/35rt. r is 3"5 mm. Widtli of arm at base is 4'2 mm. 



4/36. r is 2*9 mm. Width of arm at base is 3*5 mm. 



E. 48206. R : r : : 12'5 mm. : 3'8 mm. Width of arm at base is 4 mm. 



Horizon and Localities. — All from the Ordovician (Caradocian) of the Welsh 

 Border. 4/30 and 4/30^ are from Marshbrook, Church Stretton, 4/35a is from 

 Cynwyd (east of Bala Lake), 4/36 is from Nant Brain, 1^ miles south of 

 Llandrillo. E. 48206 is from Soudley Quarry, Church Stretton. 



One of the Asteroids from the Ruddy Collection, recently acquired by the 

 British Museum (E. 13531), is apparently very nearly related to, if it is not 

 identical with, C. caractaci. The fossil is preserved as an imprint on three 

 fragments of rock which have broken apart from each other. The moulds obtained 

 from the imprint are not very clear, but, so far as I understand them, are restored 

 in Text-figs. 42, 43. They are seen to resemble C. caractaci. The arms, 



