Anatomical Nomenclature of EcMnoderms. 19 



Illustrative Formulce. 



4.iitedon elegans A. R. 3. 2. (2) - becomes A. ^ . 3. 2. (2) . ?'. 



c 2 z 



incpqualis A. 3. ^J'^' ^'' .1 „ A. 3. ^i'l^ . ?/. 



2 1) 2 ?/ 



pon-eda A. 3. 2 j {p). br\ }~ „ A. 3. 2 { {p). h i . -L. 



-,.,,. -ry br ah e.b xy 



icftuometra solans. ... «. ix. - . — - „ a. -—- , -^. 



2 ab 2 xy 



■ pavicicirra 



Tj d.{p). br m\ c. d. (p). h /.v\ 

 ...a. K. — 2 ^^J „ a. ^ ^ J. 



— nmltibracJuata . . a. U. 3. P- P'- ■ ■■ }^'' ^r h ^^ c ^ p.p'. p^^b ;y 



z a 2 I X 



— stelUgera a. 2. 2. (2). ^ . \ „ „. 2. 2. (2). J . •?^. 



2 ab 2 xy 



5. The use of the term ^^ Axillary. '''' 



The term " axillary " was introduced by Miiller* and de- 

 fined as follows : — " Das dritte radiale hat nach oben zwei 

 dachformig geneigte Gelenkflachen fiir die beiden darauf 

 sitzenden Arme. Ich nenne es deswegen radiale axillare, es 

 ist Miller's Scapula^ dagegen nenne ich hrachialia axillaria 

 alle im Verlauf der Arme vorkommenden ahnlichen Glieder, 

 auf denen zwei Theilungsarme aufsitzen." 



The term has been generally used in the Miillerian sense 

 during the last forty years, ^'. e. only with reference to plates 

 which serve as points of division in the rays and arms, 

 whether these be free or incorporated into the more or less 

 rigid dorsal cup. Bather, however, has recently extended its 

 use in a manner which is scarcely advisable at present, since 

 it is not as yet justified by anatomical research. He has 

 applied the name to the " bifurcating piece " in locrinus which 

 gives rise both to the right posterior ray and to the ventral 

 sac t- The lowest of the series of plates supporting the ven- 

 tral sac — that which rests on the left upper edge of the bifur- 

 cating piece, and is marked x in Bather's diagram \ — is 

 regarded by him as having " originated as a plate morpho- 

 logically corresponding to an ordinary brachial ; " and he 



* " Ueber den Bau des Pentacrinus caput Meduscs" Abliandl. Berlin. 

 Akad. 1841 [1843], p. 202. 



t Ann. & Mag. Nat. Hist. ser. G, vol. v. 1890, p. 320. 

 J Ibid. pi. xiv. fig. 5. 



2* 



