1 913 ] Pack: Scutella norrisi and Scutaster andersoni 301 



The new material shows that lunules and narrow marginal 

 notches are lacking in the prolongation of the posterior petals 

 and in the posterior interambulacral area, as was suggested in 

 the original description. 



SCUTASTER ANDERSONI Pack 



Plate 15, figures 2a and 2b 

 Univ. Calif. Publ. Bull. Dept. Geol., vol. 5, pp. 278-279, pi. 23, 1909. 



The original description is as follows: 



Test sub-circular in outline, edges markedly thin. Upper surface regu- 

 larly arched from the margin; apex anterior to the center. Apical system 

 small and appjarently central. Ambulaeral star small; petals extending 

 slightly less than half way to the margin of the test, closed at the ends. 

 Lateral petals broader than the posterior ones, but of almost the same 

 length. Poriferous zones broad, and continuing full width almost to the 

 ends of the petals. In the posterior petals the interporiferous area forms 

 about one-third the width of the petal. Poriferous zones of the lateral 

 petals equal in width to those of the posterior petals, but enclosed area 

 broader. In the extension of the three anterior petals are broad lunules, 

 over half as long as the petals; shallow grooves extend from the lunules 

 to the margin. Anterior lunule slightly farther from the apical system 

 than are the lateral ones. From the ends of the posterior petals the 

 plates enlarge, and the area broadens rajnidly. No lunules were seen here, 

 nor in the posterior interambulacral space. They may be represented by 

 marginal notches, as the posterior edge of the specimen is lacking. 



The new material shows that the test is sub-circular to oval 

 in outline. The apical system is slightly posterior to the middle 

 of the test, the ratio of the distance from the apical system to 

 the posterior and anterior margins in the figured specimen is 

 as 23 :30. The middle of the arch of the abactinal suface is 

 slightly anterior to the middle of the test, being located approx- 

 imately in the middle of the anterior petal. In the figured 

 specimen the distance from' the middle of the arch to the anterior 

 margin is 21 mm., to the posterior margin 32 mm. The posterior 

 ambulacrae terminate rather abruptly, the edge of the test form- 

 ing broad, shallow notches which fashion the posterior interam- 

 bulacral area into a process somewhat similar to that of Scutella 

 norrisi. The test is much compressed. In some cases there is a 



