SCYTALOCRINUS. 235 



conical, its arm-plates seem all equal, and it appears to differ in having only one 

 row of primibrachs. 



8c. Vanhomei, Worthen, 1 is also very like, both as to its dorsal cup and its 

 ventral sac, but its arm-plates are much shorter and more cuneate. Its second 

 primibrach is axillary. 



2. Scytaloceinus AKACHNOiDKus, n. sp. Plate XXXVIII, figs. 5, 6. 



Description. — Stem round, with alternate very long and moderate columnars 

 (near the cup), which have gently convex peripheries. Dorsal cup small, appa- 

 rently semi-globose (bowl-shaped). Infra-basals elongate, pentagonal? longer 

 than wide. Basals subhexagoual, equal to the infra-basals in height but broader. 

 Radials pentagonal, about the same size as basals, convex laterally, and with 

 horizontal upper margins. First primibrachs large, square ; second primibrachs 

 pentagonal, axillary. Arms very long, simple, not perceptibly tapering, composed 

 of equal plates, which are rather higher than wide, have almost horizontal sutures, 

 and bear very long pinnules with numerous joints. Azygous plate very similar to 

 the radials, bearing apparently another very small anal on its left shoulder, and a 

 third on its truncated upper margin ; these being followed by numerous rows of 

 subhexagonal pieces forming a long narrow neck to the sac, which is longer than 

 the height of the cup, the sac then expanding and forming a long reticulate bag 

 four or five times the height of the cup. 



Size. — Height of a cup 5 mm., length of ventral sac about 40 mm. 



Localities. — There are three specimens from Barnstaple in the Woodwardian 

 Museum. 



Remarks. — These specimens appear to have very much the same characters as 

 8c. stadiodactylus, but to differ distinctly from it in the structure of their arms, 

 which are much stouter, and composed of comparatively short equal joints. The 

 ventral sac seems also very similar. The defective state of our specimens leaves 

 of course many of the characters indistinct and doubtful, but as their size 

 does not seem to exceed that of the former species, they could hardly be sup- 

 posed to be its adult condition, and must therefore, I think, be regarded as a 

 new form. 



1 1875, Worthen, « Geol. Surv. Illin.,' vol. vi, p. 517, pi. xxxi, figs. 2, 3. 



HH 



