Mr. W. K. Fisliei's Notes on Asteroidea. 107 



that of Coronaster. There is a longitudinal series of tri- 

 lobate iiifero-margiiial plates, one of qiiadrilobatc or ciuci- 

 forni supero-marginal plates, and one of ciucifortn median 

 radial plates. Tiie marginals and radials form regular 

 transverse series. On the basal portion of tiie ray there is a 

 more or less irregular zigzag series of trilobate dorso-lateral 

 plates. The primary plates either connect directly by their 

 slender lobes, or these are joined by one or two overlap|)ing, 

 oblong, intermediate ossicles. There results an oi)en, fairly 

 regular, reticulate skeleton having large tetr.igonal meshes 

 (except wiiere the dorso-lateral plates frame pentagonal 

 openings). On the outer part of the ray the longitudinal, 

 intermediate, connecting plates and the longitudinally oriented 

 lobes of the marginals and radials gradually disappear, so 

 that there remains only a series of independent, transverse, 

 slender skeletal bands, simulating those of Brisinga, but 

 having a very different history*. The skelefal meshes 

 contain numerous papula?. The form and armature of the 

 adambulacral plates are as in Coronaster. The arrangement 

 of the pedictllariai either in retractile wreaths surrounding 

 the spines or in retractile transverse cushions is not unlike 

 that found in Coronaster ■\. The mouth-plates of the Bri- 

 singidge, of Coronaster, PnUceUaster, and of Lahidiasler are 

 similar in general form, those of Lahidiaster being relatively 

 the smallest. 



The features which are chiefly relied upon to distinguish 

 the Brisingidre, and to which the family in part owes its 

 characteristic appearance, are conspicuous by their different 

 form in Lahidiaster. Such, in the Brisingidse, are the 

 elongate and peculiarly formed adambulacral plates; the 

 long needle-like siibambulaeral and marginal spines, with 

 their characteristic sacculate sheaths ; the variable but always 

 non-reticulate abaetinal skeleton of the rays ; the [)resence 

 of only crossed or forcipiform pedicellariee. 



The genus Ratlibunaster (type Rattihunaster ca^ifornicus, 



* Verril], in his ' Monograph of the Shallow-water Starfishes of the 

 North Pacific Coast,' 1914, p. 352, proposes a new genus, Labidastrella, 

 for Lahidiaster annulatus, iSladeu. ''It differs considerably in stnicturo 

 from L. radiosus, especially in having- the dorsal and superomarginal 

 plates nearly abortive distally, on the rays, beyond the genital regions." 

 It is evident that this tendency to hise the dorsal .skeleton of the distal 

 part of the ray manifests itself in L. radiosus, and is carried further in 

 L. anmdatus. I agree with Koihler that it does not form a safe basis 

 for a generic division between two otherwis^e similar species (Kcehler, 

 Ann. de I'institut oc(5auographiqne, vol. vii., fasc. 8, May 1917, p. 8). 



t See Sladen's figures oiAsterias { = Coronaster) volsellata, ' Challen- 

 ger ' Asteroidea, pi. cvii. 



