348 Dr. J. W. Gregoyy — 0)i Pakeozoic Starfishes. 



The marginal plates are large. On the abactinal surface they are 

 separated by numerous closely fitting plates, with convex upper 

 surfaces, so that they ajDpear tubercular. These intermediate 

 abactinal plates are arranged in alternate, transverse rows. 

 No carinal abactinal plates. 



Ambulacral plates traversed by strong transverse ridge. Adambu- 

 lacral plates thick and tubercular. 



Type Species. — Falceasterina Kinahani, Baily, 1879. Mem. Geol. 

 Surv. Ireland, Sheet Nos. 169, 170, ISO, 181, p. 58, fig. 6 ; p. 59. 



Affinities. 



The genus differs from Zindstromaster by its long rays and trans- 

 verse rows of abactinal intermediate plates. 



Ukanaster Kinahani (Baily), 1879. 

 Diagnosis. 



Medium-sized starfish, with B of about 30 mm. and r of about 7 mm. 

 The arms are 8 mm. across at the base. 



Marginal plates elongated in the direction of the arm ; about 30 

 supramarginals on each side of each ray. 



Abactinal intramarginal plates consist of an outer row of large 

 submarginal plates, alternating with the marginals ; small 

 plates sometimes occur in the angle between these plates and 

 the marginals. Within the submarginal jilates there is on each 

 side of the ray a row of three or four small tubercular plates. 

 There is no carinal series. 



The plates in the actinal interradial areas are irregular and 

 polygonal. 



The actinal furrow was apparently narrow, tapering gradually, 

 and deep. 



Distribution. 



Caradoc : Wexford. The above diagnosis is based on specimen 

 E 194 in the British Museum ; it was collected near Bannon. 



Family 2. PAL^ASTERINID^. 

 Diagnosis. 



Phanerozonia with the ambulacral ossicles alternate, the oral 

 armature adambulacral, and the madreporite abactinal. The 

 disc is large and pentagonal, and the rays are short and 

 separated by large interradial areas. The marginal plates are 

 smaller than the adambulacral plates. 



Affinities. 



The family agrees with the Palseasteridee in the three first 

 characters stated ; but differs from it by the shortness of the rays 

 and large size of the disc, and by the less development of the 

 marginal plates. The family differs from the Aspidosomatidte by 

 the fact that the rays are never petaloid, and by the absence of the 

 abactinal depressions between the marginal plates and the longi- 

 tudinal series of abactinal arm plates. 



