Dr. J. W. Gregory — On Palceozoic Starfishes. 353 



special marginal plates. The ambulacral ossicles are alternate 

 (or possibly sometimes opposite). Tlie disc is large, and the 

 rays short, thick, and blunt or clavate. There are no lateral 

 spines. The abactinal plates are granular and closely set. 

 1. LEPID ASTER, Forbes, 1850. 

 Dec. Geol. Siirv., No. iii, pi. i. 

 Type Species. — L. Grayi, Forbes, 1850. Op. cit. Wenlock 

 Limestone : Dudley. 



2. ETHERIDGASTER, nov. gen. 

 Diagnosis. 



Lepidasteridee with five clavate arras. The arms are covered 

 abactinally by three rows of alternating, hexagonal plates. 

 The abactinal surface of the rays is occupied by the broad 

 adambulacral ossicles. Ambulacral ossicles opposite {fide 

 De Koninck). 

 Type Species. — Palceaster Clarkei, De Koninck, 1877. Foss. 

 Pal. Nouv. Galles des Sud., pt. iii, p. 166, pi. vii, figs. 6 and 6a. 

 Falceaster {3Ionaster) Clarkei, R. Etheridge, jun., 1892. Mon. Carb. 

 Invert. New South Wales, pt. ii, p. 71, pi. xiv, figs. 1, 2; pi. xv, 

 fig. 4. Carboniferous : Farley and West Maitland, Northumberland 

 County, New South Wales. 

 Affinities. 



The type species of this genus has been admirably figured and 

 described by Mr. R. Etheridge, jun., after whom it is named. As 

 Etheridgia and Etheridgina and probably other modifications of that 

 surname are preoccupied, I follow the convenient Salteraster 

 precedent. 



Etheridge remarked that the starfish might have to be removed 

 far from Palceaster, and even from the same order. From the absence 

 of special marginal plates it appears to me advisable to include it 

 in the Cryptozonia. It is allied to Lepidaster by the heavily-plated, 

 blunt arms, large disc, and wide adambulacral plates. 



Reference to the Lepidasteridfe I'enders it advisable to remark 

 that the classification adopted in this paper is probably wrong in 

 connection with this family or with the TgeniasteridEe. The former 

 is included in the Cryptozonia, as it has no special marginal plates 

 and the adambulacral plates are very wide (transversely to the arm) 

 and resemble those of the Jurassic genus Tropidaster. It is possible 

 that Tropidaster is a later representative of the Lepidasteridse, in 

 which the abactinal plates have broken up into an irregular set of 

 granules. 



But the Tgeniasteridas, in which the adambulacral plates act as 

 marginals, and there is no special additional set of marginal ossicles, 

 I have left in the Phanerozonia. It may, however, be urged that 

 the Tgeniasterids ought to go with the Lepidasterids. The reason 

 why I have kept them apart is the idea that the adambulacral plates- 

 of Lepidasterids are true adambulacrals ; whereas in the Teeniasterids 

 these plates are rudimentary, and those described as adambulacrals. 

 are really marginal plates. 



DECADE IV. — VOL. VI. — NO. VIII. 23 



