407 
of Edinburgh, Session 1876 - 77 . 
he had prepared were published by Alexander Agassiz, with a short 
note by Count Pourtales, in the “ Zoological Results of the ‘ Hassler ’ 
Expedition.” 
During the last few years three specimens of Holopus rangii 
have fallen into Sir Rawson Rawson’s hands, and from these we 
will be able to give a pretty good account of the hind parts. All 
were brought up on fishermen’s lines from deep water off Barbadoes. 
One is very complete in all important points, wanting only the 
two “bivial” arms, but retaining the mouth-valves. The second is a 
little larger; it wants the mouth- valves, and again the bivial arms ; 
and with Sir Rawson Rawson’s sanction I boiled this specimen 
down, to figure and describe the separate parts. The third speci- 
men is quite perfect, the arms closely curled in, in their normal 
position when contracted; but it is very young, only about 8 m.m. 
in height. Besides the four examples mentioned I am aware of 
only another, which I have not yet seen ; it was shown at the Phila- 
delphia Exhibition, and was afterwards bought by the Museum of 
Comparative Zoology at Cambridge, Mass. 
Holopus is distinguished from all other recent Crinoids by hav- 
ing the basal plates, and the first and probably also the second 
radials fused together, forming the wall of a tube-like body-cham- 
ber, which is cemented beneath to the foreign body to which the 
Crinoid is attached, by an irregularly expanded calcareous base. 
This mode of attachment also occurs in the fossil genus Apiocvinus , 
and in many other forms of the Apiocrinidae and Cyathocrinidae, 
but in these, of course, the cement matter is thrown out at the 
base of a jointed stem. 
The upper portion of this hollow column expands slightly, and 
its thickened upper border is divided into five strongly-marked 
facets for the articulation of five arms. Each facet is traversed 
by a transverse articulating ridge, a little in front of which there 
is the mouth of the tube which lodges the sarcode axis of the 
joints, and a little behind its centre there is a somewhat longer 
aperture which appears to lead into the cancellated structure of the 
outer part of the wall. There are two large shallow muscular im- 
pressions on the surface of the facet on the proximal aspect of 
the transverse ridge. These facets, I conclude, represent the upper 
surfaces of second radial's, but if so, they differ from the second 
3 H 
VOL. IX. 
