II. TERMINOLOGY. 



The following terminology may be regarded as the result of a two years' 

 correspondence with the late Dr. P. H, Carpenter, carried on with a view 

 to securing greater uniformity and precision in the morphological nomen- 

 clature of the Crinoids^ and we mutually agreed to adopt it in our future 

 WTitings. On some points, Dr. Carpenter defined his own position in a |)aper 

 w^hich appeared about a year before his death.* 



Mr. F. A. Bather, in 1890, alsof agreed to accept this terminology with 

 very slight modifications, and applied it practically in his earlier descriptions 

 of British fossil Crinoids, but renounced it in 1892,.}: and proposed in its 

 place a new one, which will be discussed later on. Many of the terms which 

 are explained below are familiar to every student of Crinoids ; but as some 

 of them have been used in different senses by different authors, we include 

 them for the sake of completeness. A few of them are new ; others, though 

 used by foreign authors, have never been introduced in American Crinoid 

 literature. We believe that the terms are adapted equally well for the 

 description of recent and fossil Crinoids, pinnulate as w^ell as non-pinnulate. 

 There are a few additional terms, not of such general application, which 

 will be found explained in their proper places. 



The Crinoids, Blastoids and Cystids, with perhaps a few exceptions, 

 differ from all other Echinoderms in being at some stage of their life pro- 

 vided with a stem for attachment to other objects. This structure gives 

 rise to a difference in habit, by which they live upon the aboral side, instead 

 of creeping about mauth downward in search of food. 



The skeleton or test of a Crinoid consists of the stejn or column, and the 

 croiun. If the stem is provided with lateral appendages, these are called 

 cirri. Those of the distal end are the radicular cirri, and form the root. 

 The stem is constructed of the stem joints, of which the larger, and all cirrus- 



* '' On some Points in the Anatomical Nomenclature of the Echinoderms ; " Ann. and Mag. Nat, Hist., 

 1890 (July number). 



t British Eossil Crinoids ; ibid. (April number), pp. 306 to 330. 



X Suggested Terms in Crinoid Morphology ; ibid. (January), pp. 51-66. 



