230 



BRITISH PALAEOZOIC ASTEROZOA. 



N., that is, wo seemingly have n pentagonal form with large ventral interradial 

 areas bounded by infero-marginalia, many of which have fallen away. It was this 

 appearance which led Gregory to place the form among the Phanerozonate 

 Asteroidea. Gregory stated that " both snpero- and infero-marginals are present." 

 [ cannot see any trace of supero-marginals. 



Schuchert (1915, p 149), in his remarks on this species, stated that " it is 

 probable that the marginals in Lindstromaster which Gregory thinks are both 

 supra- and infra-marginals lying directly superposed are only infra-marginals." 

 He also states that "when more material is obtained and the genus is re-studied, 

 comparisons should also be made with Palasterina primaeva, as the two forms 



T. 



M.P 



Text-fig. 1C6. — Drawing of an arm of Palasterina antiqua (type specimen). Ad., adambulacral ; 

 M.P., mouth. angle plate ; 7'., torus. x 5. 



appear to have much in common." Prof. Lindstrom, who lent the specimen to 

 Gregory, referred the form to Palasterina. 



If the form belonged to Palasterina, many of the ossicles in the interrndii must 

 be really ossicles from the lateral surfaces squeezed into their present position by post- 

 mortem distortion. Both the original drawing and an electrotype of the specimen in 

 the collection of the British Museum (Nat, Hist.) suggested that this was the case, 

 ;ind in order to clear the matter up I applied to the authorities of the Copenhagen 

 Museum for permission to re-examine the specimen. By the courtesy of Dr. Ravn 

 this was granted. 



The arm pointing east was cleared of matrix and turns out to be a long 

 cylinder stretching to within a short distance of the odontophor. The plates in 

 the interradius are therefore those squeezed over from the neighbouring arm. A 

 drawing has been made of the first-mentioned arm (Text-fig. 160), and it illustrates 

 well the cylindrical structure and the typical Palasterina appearance. The mouth- 

 angle plates are almost exactly similar to those of /'. primaeva, and the adambula- 



