i ossn.s or THE r.ruLiXGTON c,i;orp. 329 



away. Tlie part remaining has a short, wide, sub-cylindrical form, 

 with a rather broad, obliquely truncated lower end, which is not taper- 

 ing, as in the other species. Under a magnifier it is seen to be com- 

 posed of an extremely tine net- work, far surpassing, indeed, in delicacy 

 of structure, the finest laces that it is perhaps within the power of human 

 skill to fabricate: and as it is entirely free from any surrounding matrix, 

 except at one side below, the specimen has to be handled wijh great 

 care, as a mere touch of this delicate part would probably cause it to 

 fall into hundreds of minute fragments. On examining it under a mag- 

 nifier, the little bars of which it is composed are seen not to inter- 

 each other at any uniform angle, but anastomose, so as to impart a 

 kind of irregular regularity, if we may so speak, to the form and size 

 of the meshes. Of these little bars there are two sizes, the larger form- 

 ing the larger meshes, while within the latter a smaller set of proee----- 

 nd partly or entirely across, so as to form more minute meshes; 

 the whole presenting a beautiful appearance, of which it would be diffi- 

 cult to convey a correct idea by a mere description alone, without the 

 the aid of figures. 



From analogy, judging from what is known of the internal structure 

 of the recent genus Comatula. in which several authors have noticed a 

 reticulated calcareous structure secreted within the tissue of the softer 

 parts of its alimentary canal, we may infer that this convoluted organ 

 was. as it were, a kind of frame work, secreted for the support of the 

 digestive sack, which was probably more or less convoluted in the same 

 way in many, if not all of the Palaeozoic Criiioids, though not appar- 

 ently, in all cases, endowed with the power of secreting a sufficient 

 dense structure of this kind to leave traces of its existence in a fossil 

 state. 



B far as we are at this time informed, this organ has yet been very 

 rardy observed in any other family than the Actinocrinida, though it 

 was prob ibly more or less developed in various other groups. In one 

 instance Mr. AYACILSMUTH found it in a Phitycrini'*. but here it seems 

 to be. in the specimen found, merely a spongy mass, not showing very 

 clearly the convoluted structure. Some traces of what was supposed 

 to be something of this kind were also observed by him in one of the 

 Blastoids. 



."". Amlnilacrfd canals passing under the vault in the Actinocritridte. In 

 the third and fourth Decades of descriptions and illustrations of the 

 Canadian Organic Kemains, Mr. BILLINGS, the able palaeontologist of 

 the geological survey of the Canadian provinces, gives some highly 

 interesting and instructive remarks on rtie ambulacral and other open- 

 ings of the Palaeozoic Crinoids. In these remarks he noticed at length 

 some striking ditlerences between the vault, or ventral disc, of these 



43 



