42 NEW YORK STATE MUSEUM 



formed by narrow, slightly curved plates. As to the determination 

 of these plates there is still considerable doubt. Stiirtz (op. cit.) 

 considered the pores as the podial pores and the marginal plates as 

 the adambulacrals, thus making the whole width of the ray the 

 ambulacral groove. Schondorf 1 uses the same terminology, but 

 states that the description of this starfish needs a thorough revision. 

 Schuchert (op. cit., p. 159) considers the median groove as the 

 ambulacral groove, the ambulacral plates as not seen, the adjoin- 

 ing plates as adambulacral plates and the marginal plates as infra- 

 marginals. Our material is hardly preserved well enough to decide 

 this question, and however it may be answered, the fact remains 

 that the arrangement is exactly alike in Helianthaster 

 rhenanus and Lepidasterella gyalum. 



The oral armature is splendidly preserved in one specimen of 

 L . gyalum. It is there seen to consist of a powerful frame, 

 each arch or " jaw " of which consists of four strong ossicles, two 

 long uprights and two shorter joists. The bases of the uprights 

 hold the small syngnaths (see text figs. 16 and 17). 



Lepidasterina gen. nov. 



The genus Lepidaster Forbes has thirteen arms ; Lepidasterella, 

 proposed by Schuchert, has essentially the same structure as 

 Lepidaster, but twenty-four rays. The State Museum contains still 

 another multiradiate starfish of the same family with eight rays. 

 For this the name Lepidasterina is proposed. Like Lepidaster and 

 Lepidasterella it is based only on one species. It differs from 

 these genera and Helianthaster, which also belongs in the Lepid- 

 asteridae, principally in the number of the rays, and further in the 

 very small size of its disk and the long slender form of the rays. 

 The structure of the rays, however, if we understand this genus 

 correctly, is that of Lepidaster and Lepidasterella. Corresponding 

 to the more slender form of the rays, the plates are also distinctly 

 more elongate. This is especially true of the adambulacral plates 

 which are not short, transversal as in Lepidaster, but long, some- 

 what dumb-bell-shaped, being thickened at the sutures. The infra- 

 marginals are somewhat wider. The adambulacral plates are 

 opposite, as in the other genera, in one specimen and alternating in 

 the other, thereby indicating that also the ambulacral plates which 

 have not beer: seen were very variable in their relative position. 



1 Fr. Schondorf. Die fossilen Seesterne Nassaus. Jahrb. des Nass. Verein? 

 fur Naturk. in Wiesbaden. 62 Jahrg., p. 35. 1909. 



