220 DEVONIAN FAUNA. 



Remarks. — The Croyde specimen possesses the customary indistinctness of our 

 fossils, for though both sides of the mould and the central cast are preserved, the 

 cnp is much distorted, and each side of it is obliterated. Hence its plates cannot 

 be perfectly traced; and, particularly, it seems a little doubtful whether the first 

 primibrachs are axillary, so as to produce twenty arms instead of ten; i. e. 

 whether the following series of plates are second primibrachs or secundibrachs. 

 The exposed face shows five arms, but their junction with the cup is obscure. 



In the Athenaeum specimen the stem is slight and round, and apparently bears 

 a few fine cirrhi, and (some distance from the cup) every eighth columnar seems 

 enlarged. In the cup a vertical row of five or six small polygonal plates may 

 be traced, which may be a basal, a radial, and one or two primibrachs and 

 secundibrachs, but there are too few plates shown to make their characters clear. 

 The arms are comparatively much larger and more massive, uniserial, formed of 

 rather long plates, clothed with rather sparse pinnules, and bifurcating some six 

 or eight plates up. Its identity with the former specimen is very doubtful. 



IV. Family — Actinocrinim:, F. Romer, 1855. 



1. Genus— Actinocrinus, J. S. Miller, 1821. 



1. Actinocrinus Portbri, Whidbome. Plate V, fig. 21; Plate XXX, fig. 8; 



Plate XXXI, figs. 1, la, 2, 5; and Plate XXXII, fig. 1. 



1890. Actinochinus Porteui, Whidbome. Proc. Gc<>1. As^oc, vol. xiv, p. 377. 



Description. — Column long, round, with short alternating or doubly alter- 

 nating segments. Larger columnars with a large prominent squared central 

 band occupying more than half of their flat peripheries, and with about thirty- 

 five rather stout submarginal radiations on their articulating surfaces. Central 

 canal petaliform in section, dumb-bell-shaped between the sutures. 



Calix large. Basals three (?), very narrow, hexagonal. Radials five, 

 moderate in size, hexagonal. First primibrachs similar to the radials, but rather 

 smaller. Second primibrachs rather smaller than the first, pentagonal. Secundi- 

 brachs 10 x 1, smaller than the primibrachs, pentagonal. Arms probably twenty, 

 with short plates, uniserial for the first two or three plates (which are included 

 in the cup), then biserial with alternating plates, branching at somewhat uneven 

 heights from thirteen to twenty plates up, and again at still more uneven heights 

 higher up. 



Interradials (in one interradial area) — in the first row, one plate intercalated 

 between, and of the same size as, the first primibrachs — in the second row two, 

 smaller, and situated between the first and second primibrachs — in the third row 



