442 THE CANADIAN NATURALIST. [Dec. 



era would be almost a physical impossibility. Hence he 

 concluded that the ambulacral canals mu.<t have passed directly 

 through the walls of the body at the arm-bases; and he gave 

 several figures of various types, showing openings at the base of 

 the arms, through which he maintained that the ambulacra 

 must have passed to the interior of the body from the arms. 



Although these arm-openings had long been well known to all 

 familiar with our numerous types of western Carboniferous 

 Ciinoids, in which they are very conspicuous, and we had never 

 entertained any other opinion in regard to them, than that they 

 are the only p issages of communication that could have existed 

 between the softer parts occupying the ambulacral furrows of the 

 arms, and the interior of the body, Mr. Billings was the first 

 author, so far as we are at this time aware, who called especial 

 attention to them in this regard. We regret that we have not 

 space to quote a portion, at least, of his remarks on this subject? 

 and would advise the student to read attentively the whole of 

 both of his articles alluded to. 



The specimens at Mr. Billings' command enabled him to trace 

 the courses of the ambulacral canals from the arms, through the 

 walls of the body at the arm-bases, and to ascertain the additional 

 fact that, after passing through the walls, they seemed to have 

 turned upward ; but beyond this he had not the means of tracing 

 them farther. 



A single specimen of Actinocrinus proboscidialis, however, in 

 Mr. Wachsmuth's collection, is in a condition (thanks to the 

 great skill of that gentleman, and the exceedingly fortunate state 

 of preservation, by which its delicate internal parts remain almost 

 entire, and without any surrounding matrix) to throw much 

 additional light on this subject. By very dextrous manipulation^ 

 Mr. Wachsmuth succeeded in removing about half of its vault, 

 so as to expose the internal parts, in place, and in an excellent 

 state of preservation. The convoluted organ already described in 

 other species is in this comparatively large, sub-cylindrical in the 

 middle, apparently tapering at the lower end, and a little dilated 

 at the upper extremity. It seems to be rather dense, and shows 

 the usual rough appearance, but as we had no opportunity to 

 examine any detached fragments of it by transmitted light, we 

 did not determine whether or not it has pores passing through it^ 

 though it probably has, at least when entirely free from any 

 inorganic incrustation. Its slightly dilated upper end seems to 



