SALTBRASTER ASPERRIMUS. 



151 



to somewhat similar ossicles in species of Promopalaeaster are made in the previous 

 section of this monograph (pp. 91, 92). The reference made on p. 92 to U. yrimxva 

 is wrong. This species (8. asperrimus) should have been named. 



The photograph of the cast does not give a good idea of the length of the 

 paxilla-shafts. The moulds show deep pits, but it is not easy to get good casts 

 from these. The height of the shaft is best shown in Text-fig. 95. 



Text-fig. 95. — Cross-section through the arm of Salteraster asperrimus. Ad., adambulacralia ; 

 I.M., infero-marginalia ; R., radialia. x 10. 



The arrangement of the plates of the disc is not certain. All the specimens 

 suggest that the adradialia and radialia follow the Urasterellid disposition as shown 

 in Text-fig. 81. The holotype shows a madreporite, and I think that I can 

 recognise a centrale and a primary circlet of plates in 25335 and 25336. 



A slight displacement of the plates in 25335 allows one to get a good apical 



96 



97 



Text-fig. 96.— Plan of the oral surface of Salteraster asperrimvs. O., odontophor. x 2\. 

 Text- fig. 97. — Wash drawing of the adambulacralia at the extremity of the arm of Salteraster 



asperrimus. x 6. 



view of the ambulacralia, These are thick and high, exactly as described for 

 JJ. pulchella by Hudson (93, pp. 124 and 136). The thick ambulacralia in them- 

 selves cause the arm to appear convex (Text-fig. 95). 



Oral Surface (Plate XI, fig. 4; Text-figs. 96, 97).— In the Text-figures the 

 groove is shown as closed. The whole breadth of the arm is occupied by the 

 stout adambulacralia which completely hide the ambulacralia. 



The mouth-parts are almost exactly as in Urasterella. The more proximal 



