52 .. ° My. F. A. Bather— 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, either 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 importance 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 that 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 with 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. 
Super-radials and Infer-radials. 
Many of the Monocyclic genera of Crinoidea Inadunata are 
remarkable for the transverse bisection of some or all of the 
radial plates of the dorsal cup. To these radially situated 
plates themselves the term “ Radials” 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 Rs and R¢. Instead of saying “ the 
lower half of the left anterior radial,’’ we shall now be able 
to say “ the left anterior inferradial” (1. ant. R¢). The plate 
for which the term Radianal (R’) has been adopted is of 
course the right posterior inferradial (r. post. R¢) ; while the 
right posterior radial, being the upper half of the same plate, 
is morphologically the right posterior superradial (r. post. Rs). 
Arm-ossicles. 
In July 1890 the following terminology was proposed for 
the various series of arm-ossicles by P. H. Carpenter * :— 
*Opicitapaels 
