Retrospective Criticism, 7S> 



Mr. Gilbertson^s idea), which he describes as being in its pro- 

 per place, in my figure, on the left of the column, is nearly as 

 large as that part of the column which I have supposed to be 

 extraneous. This scapula must rest upon a costal, and this 

 costal upon a pelvic bone, or rather upon two pelvic bones ; 

 the costal upon which this scapula rests must be as large as 

 the scapula itself; and the pelvic bones upon which the 

 costal rests must be of equal dimensions : therefore, if the 

 scapula be nearly equal in size to the column, the sca- 

 pula, costal, and pelvis, united, must of necessity be much 

 larger ; and yet Mr. Gilbertson says, that, in my specimen, 

 the column hides nearly the whole of these bones : this is a 

 physical impossibility, for the thing covered is of greater 

 magnitude than that which is said to cover it. Again : that 

 the angular bones, in my specimen (VI. 126.), and to 

 which I have referred in VI. 472., are really the bones 

 of the pelvis, is, I think, absolutely proved by their position. 

 The costals are placed upon the pelvis, I believe in every 

 instance, in this way : one costal rests upon part of two pelvic 

 bones, and covers the joints formed between them ; and thus 

 locks them together, precisely in the same way as a bricklayer 

 places one brick to cover portions of two others, in laying one 

 course over another, in building a wall : and this is exactly 

 the position they occupy in my figure. If this bone were the 

 scapula, the angular bone (the costal of Mr. Gilbertson) must 

 have had a joint in the angle, in a line with the joint between 

 the supposed scapulae ; but in my figure there is no such 

 division. If the column absolutely '' covers the whole of the 

 pelvis, and nearly the whole of the costals," it appears to me 

 difficult to account for the use of the pelvic or costal plates ; 

 for by this means they would be united into one solid mass, 

 and, therefore, their division into plates would appear to be 

 almost useless. In conclusion, Mr. Gilbertson accuses me of 

 constnicting a nondescript. Whether he means this in good 

 part or not, I can hardly say. I have already acknowledged 

 that, in my opinion, it had not " hitherto been figured or 

 described ; " and it was because I considered it a nondescript 

 that I communicated it to this Magazine, and endeavoured to 

 furnish a description of it. If nothing is to be made public 

 but what is already described, then must science have already 

 reached its limits; and the naturalist may sit down in listless- 

 ness, and exclaim, " There is no new thing under the sun ! *' 

 Mr. Gilbertson sums up his observations by stating, that it is 

 a desire to check the progress of error that alone has induced 

 him to controvert my statements ; I beg to inform him that 

 there is no other motive influencing me. I am not at all 

 anxious to prove that I am in possession of the lily encrinite 



