Dr. J. W. Gregory — On Palceozoic Starfishes. 345 



11 or 12 on each side of each ray. They are large, and the 



exterior side is tumid. 

 On the abactinal surface of each ray there appear to be three 



rows of small plates, of which those of the median series are 



the lai'gest. 

 The madreporite is large, and placed close by one of the interradial 



angles. 



Dimensions. 



B.M., 48,206. 



R 12 mm. 



r 3-5 ,, 



Width of arm at the base 3-o ,, 



Distribution. 



Caradoc Sandstone. ? Soudley Quarry, Church Stretton, The 

 specimen on which the above diagnosis is based is contained in 

 a small nodule, and is labelled from the Soudley Quarry. Mr. R. A. 

 Buddacombe has, howevei", expressed doubt as to the exact 

 correctness of this locality. The specimen is in the British 

 Museum Collection (No. 48,206). 

 Affinities. 



This species was recorded by Salter^ in 1865, but I am not 

 aware that any description has been published. R. Etheridge, jun., 

 and Nicholson remarked that the species is a true Palceaster, an 

 opinion no doubt based on the specimen here described (British 

 Museum, No. 48,206). 



The nearest ally of this species is P. maliUina (Hall),^ from 

 the Trenton Limestone in the State of New York, which has 

 a single row of large plates filling up the space between the 

 marginals on the abactinal side. 



2. AEGASTER, Hall, 1867. 



Note on Talaaster, 20th Rep. Eeg. Univ. New York, p. 287 ; aud Nicholson & 



Etheridge, jun., Sil. Foss. Girvan, 1880, p. 322. 



Type Species. — Asterias antiqua, Troost, 1835. Trans. Geol. 

 Soc. Pennsyl., vol. i, p. 232, pi. x, fig. 9. 



? 3. TETRASTEE, Etheridge, jun., & Nicholson, 1880. 

 Sil. Foss. Girvan, p. 324. 

 Type Species. — Tetraster TFyinlle-Thomsoni, Eth., jun., & Nich., 

 1880. Op. cit., p. 324, pi. xxi, figs. 1-8. 



4. PETRASTER, Billings, 1858. 



Dec. Geol. Surv. Canada, No. iii, p. 80. 



Type Species. — Palceasterina rigidus, Billings, 1856. Rep. Geol, 



Surv. Canada, 1856, p. 291. Petrnster rigidus, Dec. Geol. Surv. 



Canada, 1858, vol. iii, p. 80, pi. x, fig. 3. Trenton Limestone : 



Ottawa. 



5. MONASTER, Etheridge, jun., pars, 1892. 

 Mon. Carb. Invert. New South "Wales, pt. ii, pp. 70-1. 

 Type Species. — Palcea&ter (Monaster) giganteus, R. Etheridge, 

 jun., 1892. Op. cit., p. 74, pi. xii. 



^ Asterias matufiiia, Hall, 1847 : Pal. New York, vol. i, p. 91, pi. xxix, fig. 5. 

 Falaaster matidina, Hall, 1867 : 20th Reg. Rep., p. 283, pi. ix, fig. 2. 

 2 Salter: Cat. Foss. Mus. Pract. Geol., p. 30. 



