138 SMITHSONIAN INSTITUTION 



Lecanocrinus bacchus (Salter) 

 Plate II, figs. 25-28 



Ichthyocrinus Bacchus Salter, Cat. Cambrian and Silurian Fossils, 1873, p. 126. 



A small species. Crown ovoid, widest at IAx, where height to width is 

 1 to \.2 ; at RR, i to 1.6; base rounded ; rays uniformly increasing in width from 

 RR to IAx. Surface smooth. Maximum crown, 12 mm. high by 11 mm. wide 

 at IBr 2 ; at top of RR, 4.7 by 8 mm. ; column facet, 2 mm. 



IBB small and slightly protuberant. BB small. Anal x and RA both small, 

 the former acuminate above and projecting to nearly half its height above the 

 radials. RR small, barely twice the length of succeeding IBr, and widest at 

 upper margin. Height of B to R to IBr, 2.5:2.5:1.7. IBr 2, large, increasing 

 in width upward continuous with the widening of the radials. IIBr 4 or 5. 

 Arms flat or gently rounded, not tapering rapidly between the bifurcations, and 

 disappearing by infolding at about the fifth tertibrach. Column composed of 

 nearly uniform columnals without visible alternation; a few at the proximal end 

 thinner than those below. 



The description of this species is based upon two nearly perfect specimens from the 

 Wenlock limestone at Dudley, one in my own collection (PI. II, figs. 28a, b), and the other 

 in the British Museum (fig. 27). The first of these has some peculiar surface markings in 

 the nature of depressed areas in the middle portion of the plates. Upon the basals the depres- 

 sion conforms to the outline of the plates, but on the radials and brachials it is crescent 

 shaped, curving down from the upper margin. Although very distinct in all the exposed 

 parts, I cannot consider this sculpturing as anything of specific importance ; the other speci- 

 men figured, in which the surface is in perfect condition, shows no trace of it, and it is also 

 wanting on another less perfect specimen not figured. I am confirmed in this view by the 

 fact that something of the same kind is found occasionally in other species, e. g. in L. macro- 

 petalus (PI. Ill, fig. 8a). It is also faintly indicated in the basals of L. lindstromi (PI. II, 

 fig. 22b), and must have been seen on some specimen of L. facietatus to suggest the appear- 

 ance shown in Angelin's figures on plate 21 of the Iconographica. 



The proportions of the plates in the brachial series are such that there is a gradual widen- 

 ing of the rays from the radial to the upper primibrach, producing that lack of differentiation 

 between calyx and succeeding parts characteristic of Ichthyocrinus. This aspect is accentu- 

 ated by the relatively increased length of the primibrachs. In these particulars this species 

 is similar to L. meniscus from Tennessee, but differs from that species as well as from 

 L. lindstromi in the form of the anal plate. 



In J. W. Salter's Catalogue of Fossils in the Geological Museum of Cambridge Uni- 

 versity, 1873, P- I2 6» ne gives Ichthyocrinus bacchus as a manuscript name for a form num- 

 bered 0.528 in the collection, and comments upon it as follows : " The depressed short form 

 and very short plates so much resemble those of Taxocrinus nanus, that some close observa- 

 tion is needful to distinguish this, which has no interradial plates, from the former which 

 possesses very narrow ones." The reference to Taxocrinus nanus, another unpublished 

 species, does not help much, although I am now aware that it is the form first described by me 

 as Homalocrinus dudleyensis, but herein referred to H. parabasals. But I have been favored 

 by Dr. Woods, of the Sedgwick Museum, with photographs of the two specimens bearing 

 Salter's label as the types of his species, one considerably larger than ours (PI. II, figs. 25, 26). 



