444 THE CANADIAN NATURALIST. [DcC. 



The presence of furrows radiating from the central region of 

 the under side of the vault to the arm-openings, in various types 

 of Palaeozoic Crinoids, must have been frequently observed by all 

 who have had an opportunity to examine the inner surface of this 

 part. Messrs. DeKoninck and Lehon figure a portion of the vault 

 of Actinocrinus stellaris in their valuable Reclierches mr les 

 Crinoides du Terr. Carh. de la Bdglque, pi. iii, fig. 4 f , showing 

 these furrows, which they seem to have regarded as the impres- 

 sions left by the muscles of the viscera. The inner surface of the 

 vault of most of our western Carboniferous Crinoids is known to 

 have these furrows more or less defined, either from specimens 

 showing this inner surface, or from natural casts of the same. 

 In some instances they are very strongly defined from the central 

 region outward to the arm-bases, to each of which they send a 

 branch. In Actinocrinus ornatua, Hall, for instance, they are 

 generally so strongly defined as to raise the thin vault into strong 

 radiating ridges, separated by deep furrows on the outer side. 

 In Strotocriniis, the vault of which is greatly expanded laterally, 

 and often flat on top, these internal furrows, in radiating outward, 

 saon become separated by partitions, and as they go on bifurcat- 

 ing, to send a branch to each arm, they actually assume the 

 character of rounded tubular canals, some distance before they 

 reach the arm-bases. 



That these furrows or passages of the inner side of the vault 

 were actually occupied during the life of the animal by the 

 arabulacral canals as they radiate from the top of the convoluted 

 digestive sack to the arm-openings, we think no one will for a 

 moment question, after examining Mr. Wachsmuth's specimen of 

 Actinocrinus proboscidia/is, which we have described, showing 

 all these parts in place. It is also worthy of note, that in all the 

 specimens of various types in which these furrows of the under 

 side of the vault are well known, whether from detached vaults, 

 or from casts of the interior of the same, they never converge 

 directly to the opening of the vault, but to a point on the anterior 

 side of it, whether there is a simple opening or a produced 

 proboscis. The point to which they converge, even in types 

 with a decidedly lateral opening of the vault, is always central or 

 very nearly so, and even when the opening is nearly or quite 

 central, the furrows seem to go, as it were, out of their way to 

 avoid it, those coming from the posterior rays passing around on 

 each side of it to the point of convergence of the others, a little in 



