PROMOPAL^ASTER ELTZ^. 



represent that typical of a primitive stage of the genus. No other specimen shows 

 quite such a regular arrangement, but adradialia present on the distal extremities 

 of several individuals occasionally show a distinct triangular shape. The inter- 

 marginal area possesses four rows of ossicles at its widest point. It gradually 

 narrows down to a single row, which persists as far as the sixteenth supero- 

 marginal. 



Oral Surface (PL IV, figs. 2, 3, 5; Text-figs. 54a, 55, and 55).— The oral 

 surface presents many interesting features. The interbrachial area is relatively 

 simple, somewhat as in the American species P. exsculjjtus. Only the first two 

 infero-marginalia touch one another on their outer edges. The bases of the next 

 two infero-marginalia, however, closely approximate to one another. The 

 odontophor has been forced inwards so that it is entirely proximal to the 

 infero-marginalia (Text-fig. 55). 



The mouth-parts, however, are very complex, and appear to be closely similar 

 to those of P. magnificus. They are best shown in D. 51. Details are added 



Ad. 



PROXIMAL. 



R. Ch. 



\ 



/ 



1 



1 



[ li!iT«ri'^^ ) 



( , 



WA 



yi. ) 







Text-fio. 54 a. — Oral view of ambulacralia and adambulacralia of Promopaliz'aster elizce. Ch., ainbulacral 

 channel ; R., ambnlacral ridge ; Ad., adambulacralia. (This figure is repeated from Text-fig. 18, p. 20, 

 of the Introductory Section to this Monograph.) 



from D. 215c and D. 95. The mouth-angle plates are relatively stout, and not in 

 series, as is usual, with the adambulacralia, for they themselves have adambulacralia 

 attached to them (Text-fig. 55). Several ambulacralia fit on to the mouth-angle 

 plates. A side view of these ambulacralia showing their mode of fitting on to 

 the mouth-angle plate is given (PI. IV, fig. 3), and may be usefully compared 

 with fig. 1 of pi. xxiii in Schuchert's paper. A dissected oral view is also given 

 (Text-fig. 54 a). 



The first ambulacralia are short stout plates, quite unlike those seen in any 

 other form. Their inner extremity is hollowed away, and this hollow is obviously 

 a continuation of a hollow at the proximal edge of the mouth-angle plates. The 

 two hollows together form a receptacle for the first tube-feet. The second 

 ambnlacral is also somewhat short. It fits on to a small triangular depression 

 situated at the base of a ridge upon the mouth-angle plate which divides the 

 depressions for the first and second tube-feet. The median ridge of the second 

 ambulacral is almost parallel with that of the first ambnlacral. The third and 

 fourth ambulacralia are broad ossicles. Their median ridges form a V, as do the 

 median ridges of each couple of succeeding ambulacralia up to the fifteenth member 



