52 Mr. F. A. Baiher— Suggested 



axiomatic that "whenever the bounds of knowledge are 

 extended, either by the investigation of new problems or by 

 the re-examination of old ones with the aid of improved 

 methods and extended views, an elaboration of nomenclature 

 is inevitable. Indeed, the introduction of an extended termi- 

 nology, eitlier because of the discovery of new facts or of the 

 more accurate grouping of old ones, is a distinct gain ; it 

 emphasizes an actual advance in knowledge." " In morpho- 

 logical nomenclature suitability is of far more importaTice than 

 priority, and the most respectable and time-honoured termi- 

 nology should never be allowed to stand in the way of one 

 by which homologies, mutual relations, &c., are adequately 

 expressed." 



To those who deem it hardly fitting tliat one who has so 

 recently entered on the field of Echinoderm morphology 

 should be already running atilt at terms that have long held 

 the ground, no other reply is needed than that the proposed 

 terms were arrived at after considerable discussion witli Dr. 

 P. H. Carpenter, and that nearly all received his definite 

 approval. Without his encouragement this paper would not 

 have been written, and it has only been the sudden removal 

 of his kindly help that has prevented its earlier completion. 



Siiper-radi'als and Infer-radials. 



Many of the Monocyclic genera of Crinoidea Inadunata are 

 remarkable for the transverse bisection of some or all of the 

 radial ])lates of the dorsal cup. To these radially situated 

 plates themselves the term " lladials " is restricted, but it is 

 convenient to have some short term to express their upper 

 and lower halves. For these therefore I propose the terms 

 " Super-radials " and " Infer-radials," which may be repre- 

 sented symbolically by Il« and R^ Instead of saying " the 

 lower half of the left anterior radial," we shall now be able 

 to say " the left anterior infcrradial " (1. ant. 1\«). The plate 

 for which the term Eadianal (R') has been adopted is of 

 course the right posterior infcrradial (r. post. R«) ; while the 

 right posterior radial, being tlie u|)per half of the same plate, 

 is morphologically the right posterior superradial (r. post. R«). 



Arm-ossicles. 



In July 1890 the following terminology was proposed for 

 the various series of arm-ossicles by P. H. Carpenter * : — 



• Op. at. p. 11. 



