CARBONIFEROUS FOSSILS OF IRELAND. 181 



ACTINOCRINUS. Mill 

 Gen. Ch. — Plates oftlie pelvis, three, supporting six first costal plates, one pentagonal and five hex- 

 agonal ; eleven second costal and intercostal plates bearing five scapula;. Column and alimentary canal 

 round. 



AcTiNOCRiNUS AMPHORA. Gilbertson. 



Molocrinites ampliora. Gold. — Actinocrinus amphora. Portk. Geol. Eep. 



Sp. Ch. — Spheroidal, very much depressed; pelvis small, of three pentagonal plates; first costals five hex- 

 agonal and one pentagonal ; lengtli t\vo-tl\irds tlic width ; second costals very shallow, twice as wide as long ; 

 intercostals lic.xagonal : arms very large, thick, having each near the base on the upper surface, a very promi- 

 nent, tubercular plate ; proboscis very large, lateral ; with five very prominent, convex plates at its base ; surface 



of all the plates carved with close irregular flexuous ridges, edges striated. 



« 



Actinocrinus constrictus. M'Coy. (PI. XXVII. fig. 3). 



Sp. Ch. — General figure lengthened, globose ; constricted round the middle ofthefirst costals, below which 

 the lower portions expand again, forming with the pelvis a broad, tumid base; pelvis broad, hexagonal, of three 

 plates; first costals, five hexagonal, and one pentagonal, very large, the length of the hexagonal ones equal to 

 their greatest width, the pentagonal one is somewhat narrower ; they all have the upper third flat, or slightly 

 concave, and the lower two-thirds very convex outwardly ; second costals, five, hexagonal, length one-fourth 

 less than the width, and little more than one-lialf the length of the first costals ; intercostals large, hexagonal, 

 their length exceeding the width by about one-third, width equal to that of the second costals. 



The great size of the first costals, the transverse constriction of the body, aud the inflated form of the lower 

 part of the cup and pelvis, distinguish this readily from the other described species of Actinocrinus. Length of 

 body one inch seven lines, diameter at the base of the arms one inch four lines. Presented by Mr. Charles B. 

 Newenham of Cork. 



Actinocrinus costus. M'Coy. (PI. XXVI. fig. 2). 



Sp. Ch. — ScapuliE hexagonal ; first costals longer than wide; costal and intercostal plates very large ; a 

 fourth pentagonal, interscapular plate adheres over a heptagonal intercostal, above the irregular first costal. 



The hexagonal scapulse distinguish this fine species from the A. triacontadactijlus, Mill., and the A. tes- 

 sellatus, Phil. ; the disproportionally large costal and intercostal plates distinguish it from all others of the genus, 

 even when too imperfect to shew the scapulise. The general form is pear-shaped, rather narrower than A. tria- 

 contadactylus ; the pelvis is large ; the first costals are of the usual form, very large ; the second costals hexa- 

 gonal, and longer than wide ; scapula hexagonal, also longer than wide ; the intercostal plates are hexagonal, 

 large ; one of them over the irregular first costal is heptagonal, its superior angle being truncated to support a 

 fourth interscapulary plate. The muscular markings of the plates are very well shewn in the specimen 

 figured. 



Actinocrinus Gilbertsoxi. Mill MSS. 



Actinocrinus Gilbertsoni. Phil. Geol. York. 



Sp. Ch. — Second costals twice as wide as long; all the plates minutely sculptured. 



The specimens of this species which have occurred were very imperfect, but the great width of the costals 

 and the peculiar sculpturing of the plates, will serve to distinguish the species from all, except the A. 

 amphora, of which it may be a variety. The specimens I have seen were smaller than that species, and the 

 sculpturing of the surface finer. 



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