88 BRITISH PALEOZOIC ASTEROZOA. 



remaining radialia are of the usual type, tliat is, they are breastplate-shaped 

 in the proximal region, and become polygonal distalwards. 



With respect to the remaining structure of the arm, it is necessary to state that 

 the arms in the specimen photographed (PI. II, fig. 9) are somewhat flattened l)y 

 post-mortem compression. The text-figure restoration gives the view as is shown 

 by casts from the second specimen on D. 74, which has not been flattened in this 

 way. The arm in consequence appears higher and narrower, and much more like 

 that of M. primus. 



Textfig. 47. — Plan of the oral surface of one arm and the mouth-region of Meiopalauster complicalus 



(based on D. 74). x 12. 



The points noted in the specific characters given above are, however, quite 

 clear in the photograph. The arm of M. complicates is longer and the adradialia 

 are more distinct than those of M. primus. 



Oral Surface (Plate III, fig. 5; Text-figs. 47, 48).— At first sight there seem 

 to be comparatively fewj3oints of essential difference between the oral aspect of 

 M, primus and that of the species under description. I believe, however, that 

 the possession by the latter of an increased number of adambulacralia in com- 

 parison to the infero-marginalia is a point of some im23ortauce. It was remarked 

 that no view of the ambulacralia of M. inimus could be obtained. Fortunately, 

 the ambulacral groove of the holotype of M. complicatus is widely open in the 

 mouth-region, and the structure thus presented is of great interest. It will be 

 seen from Text-fig. 48 that the ambulacral ridges tend to form Vs, and the tube- 

 feet would therefore be quadriserial rather than biserial in arrangement. Again, 



