226 DEVONIAN FAUNA. 



least an additional type." The latter might perhaps have value as an explanatory 

 species, but it is evident that to raise it to equal rank with P. crassus, Miller, 

 may only make confusion worse confused. The true remedy would be a re- 

 description of P. crassus from the original figured type (now in the Bristol 

 Museum), and other carefully identified specimens of it from the same beds. As 

 a matter of fact, it is very questionable whether Wachsmuth and Springer are 

 even right in supposing that P. notabilis belongs to the same group of species. 

 I have not been able as yet to examine closely the specimens in the Bristol 

 Museum, but from what I am able to see of them lam inclined to think P. crassus 

 may be found to have several rows of primibrachs in at least one of its arms, as 

 stated by Austin, 1 and therefore that the primibrachs are variable in the genus, 

 as stated by Sladen, 2 whereas P. notabilis (and therefore, according to Wachsmuth 

 and Springer, the genus Poteriocrinus s ) has one row only. 



1. Potehioorinus tensus, Whidbome. Plate XXXV, figs. 1 — 2; Plate XXXVIII, 



fig. 1. 



1896. Poteriockintts tensus, Whidbome. Proc. Geol. Assoc, vol. xiv, p. 377. 



Description. — Columnars very short, with smooth peripheries. Dorsal cup 

 high, conical. Infra-b'asals five, large, pentagonal, as high as wide. Basals five, 

 hexagonal ?, very high. Radials rather shorter than basals, inversely pentagonal, 

 with excavated upper margins. First primibrachs sometimes axillary ? Arms very 

 long, uniserial, bifurcating twice, composed of truncate cuneate plates. Pinnules 

 rather few, slight, extremely elongate, with ten or twelve distant joints. Anal 

 plates three. Ventral sac large, cylindrical, very long, with regular longitudinal 

 undulations, and composed of about six rows of very numerous, subquadrate, 

 slightly transverse plates with linear slits and lateral perforations. 



Size. — A cup with portions of the arms is 80 mm. long. 



Localities. — In the Woodwardian Museum is a specimen of the cup and arms, 

 and another of a detached ventral sac from Barnstaple ; in Miss Partridge's 

 Collection a specimen of the cup and expanded arms from Saunton Hotel ; and in 

 the Porter Collection a ventral sac from Pilton. 



Remarks. — Our specimens do not show the characters very clearly ; but on 

 the whole, taking the Woodwardian specimen as the type, the species seems to 



1 1850 ? Austin, ' Mon. Rec. Foss. Criiioid.,' p. 71. 



2 1S77, Sladen, ' Proc. W. Rid. York*. Geol. Polyt. Soc.,' n. s., vol. i, p. (3). 



3 1S8G, Wachsmuth and Springer, ' Proc. Acad. Nat. Sci. Philad.,' 1886, p. 158 ; but «ee 1897, 

 Wachsmuth and Springer, 'N. Ainer. Crinoid. Camer.,' vol. i, pp. 78, 151. 



