180 SYNOPSIS OF THE CHARACTERS OF THE 



CyATHOCRINUS PINNATUS. Goldf. (?) 



Cyathocrinus pinnatus. Gold. Pet. (7) — Cyathocrinus piimatus. Phil. Pal. Fos. 

 Only columnar joints of this species have as yet been observed in the Irish carb. series ; they are monili- 

 form, elliptical, thin, alternately larger and smaller ; the circumference prominent, with distinct striae of articu- 

 lation ; centre concave, nearly smooth ; canal pentagonal. 



Cyathocrinus planus. Mill. 



Cyathocrinus planus. Mill. Hist. Crin. 



A few obscure, columnar joints, agreeing in general character with this species, have occurred; they are 

 nearly equal, circular, smooth ; circumference striated ; alimentary canal small, round. 



Cyathocrinus variabilis. Pliil. 



Cyathocrinus variabilis. Phil. Pal. Fos. 



This, as a species, has scarcely any definite character ; it is convenient, however, to refer to it all those in- 

 determinate, small, circular, tlun joints of Cyathocrinus, having strongly striated, articulating surfaces, and a 

 small pentagonal, or pentaphylloidal alimentary canal ; no stress, however, should be laid by the geologist on 

 its occurrence In any particular stratum, for the above reason. 



Ehodocrinus (Gilbertsocrinus) abnormis. M'Coy. (PI. XXVI. fig. 3). 



Sp. Ch. — Scapulse heptagonal, two pentagonal and three hexagonal intercostals. 



This fine species differs from all of the genus in having the scapulse heptagonal, and three of the intercostal 

 plates being hexagonal ; differing thus in some manner from the characters of the genus, as laid down by Professor 

 Phillips, and being itself a remarkably fine species, I shall give a somewhat detailed description of Its structure. 

 Like most of the genus its general form is hemispherical, with the pelvis concave outwardly ; all the plates are 

 very convex, so as to give a nodular appearance to the body ; the pelvis is small, the suprabasal joints are five, 

 hcxao-onal, and rather longer than wide ; alternating with, and above these are five very convex, heptagonal, 

 first costals, on each of which rests a hexagonal second costal ; this plate is the most regular and constant In 

 form of the whole animal; it is longer than wide In the present species; on its upper edge rests a large heptago- 

 nal scapula ; this plate, in all the others of the genus. Is small and pentagonal, on the superior lateral edges are 

 placed two small, hexagonal first arm-joints, having above and between them a small pentagonal, clavicular 

 plate, and laterally two horse-shoe shaped joints, from which the hands proceed; on the superior edge of three 

 of the suprabasal joints rests a hexagonal. Intercostal plate, having above them several rows of Irregular Inter- 

 costals, as In the genus Bhodocrinus. The proboscis is nearly central and elevated. Length of base one Inch 

 three lines, width one inch five lines. 



Rhodocrinus verus. Mill. 



Ehodocrinus verus. Mill. Hist. Crin. 



Columns, possibly referrlble to this species, occur rather rarely, they agree in general size, form, striae 

 of articulation, and pentaphylloidal canal, with the columns referred by Miller to the present animal, but the 

 identification of columns of Crinoidea, and referring them to their appropriate bodies. Is a task of such great 

 difficulty, that, geologically speaking, it Is, perhaps, better either to take no notice of unconnected stems, or, 

 where they are very characteristic of any particular bed, to give them distinct provisional names for reference. 



