172 BULLETIN 88, UNITED STATES NATIONAL MUSEUM. 



original generic definition and when none actually applies, then the 

 fii'st species following the generic diagnosis. That Gregory fully 

 appreciated the structural difference between Palxaster clarkei and 

 P. (31.) giganteus is shown in his reference of the former to the order 

 Phanerozonia and the latter to the Cryptozonia. Our disagreement 

 is not as to structure but in the interpretation of the rules of nomen- 

 clature. Under these circumstances P. darlcei is retained as the geno- 

 type of Monaster, since it appears that P. giganteus has both infra- 

 marginals and adambulacrals on the actinal side, a structure quite 

 different from that described for and present in Monaster Etheridge. 



After the above was written in 1900, the writer explained by letter 

 to Professor Etheridge what Gregory had done. Etheridge replied 

 under date of June 6, 1900: "The laws of zoological nomenclature 

 should have guided Doctor Gregory to have selected the first species 

 described, as the subgeneric type, in the absence of any statement to 

 the contrary on my part. As you say, Etheridgaster is certainly a 

 synonym of Monaster J' 



Monaster is most like Hudsonaster. It retains the primitive pon- 

 derous skeleton of the latter, but curiously has lost the inframarginal 

 columns of ossicles, although the supramarginals are present. 



MONASTER CLARKEI (De Koninck). 



Palaeaster clarkeiDE Koninck, Mem. Soc. roy. Sciences, Lifege, ser. 2, vol. 2, 1877, 

 p. 166, pi. 7, figs. 6, 6a; (David), Mem. Geol. Surv. New South Wales, Pal. 

 No. 6, 1898, p. 127, pi. 7, figs. 6a, 66. 



Palxaster {Monaster) clarkei Etheridge, jr., Mem. Geol. Surv. New South Wales, 

 ■ Pal. No. 5, pt. 2, 1892, p. 71, pi. 14, figs. 1, 2; pi. 15, fig. 4. 



Etheridgaster clarkei Gregory, Geol. Mag., dec. 4, vol. 6, 1899, p. 353. 



Of this species three natural molds have been found in the ''Upper 

 Marine" and "Lower Marine" series (Carboniferous) of Northum- 

 berland County, New South Wales. The holotype in the Clarke 

 collection was destroyed by fire. 



The species attained a large size, the rays from the center of the 

 disk to their extremities are not less than 5 cm., and in another 

 specimen are 6.5 cm. 



URASTERELLIDiE, new family. 



Tatniasteridx Gregory (part), Geol. Mag., dec. 4, vol. 6, 1899, p. 351 (includes 



Tseniaster, fStenaster, Urasterclla, Protasteracanihion , Salteraster). 

 Roemerasterinse Gregory, Treat. Zool., vol. 3, Ecliinoderma, 1900, p. 255. 



Specialized Cryptozonia, with alternate ambulacra, and with adam- 

 bulacral type of oral armature. Kays five, rather flexible, long and 

 gently tapering, proximally united without forming interbrachial 

 areas. No inframarginals discernible as such at maturity, the actinal 

 margin being occupied by well-developed adambulacrals. Abactinal 

 area composed of numerous small plates arranged in columns and 



