REVIEWS 223 
abundance, their peculiarities in geographic and geologic distribution, 
and their structure, the stalked feather stars or stone-lilies are preémi- 
nent. With the skeletal parts composed of regular plates or ossicles, 
definitely grouped and frequently highly sculptured, all structural 
changes are readily deciphered. 
The work on the crinoids is the outgrowth of studies begun more 
than twenty years ago, under the encouragement of Louis Agassiz, and 
prosecuted without intermission ever since. The entire work as con- 
templated will form two huge quarto volumes, of which the first, in two 
parts with an atlas of plates, has just been issued. Of the text there 
are nearly 800 pages; and the plates number 83, comprising 1500 illus- 
trations artistically reproduced as photogravures. In the present 
installment—the Crinoidea Camerata—there are three main subdivis- 
ions; introductory, morphological and descriptive. 
The introduction embraces an historical résumé of opinion and a 
fullexplanation of the terminology employed in description. Special 
attention should be called to the clear and concise definitions given of 
the various structural parts. The terms should be universally adopted 
as they form by far the best collection ever proposed. American wri- 
ters especially will need no appeal to at once use them not only to 
secure uniformity in nomenclature but precision of description. Here- 
tofore the names of the various plates or groups of ossicles have been 
used in a rather haphazard way. Not only have different designations 
been given to the same part, but the same title has been repeatedly 
applied to structures widely separated morphologically. 
The morphological part contains the full discussion of the data 
upon which the entire classification of the crinoids rest, of the genetic 
relationships of the various groups, and of the structural characteristics. 
The plates in general are separated into ‘‘ Primary ”’ and “ Supple- 
mentary’”’ pieces. The former occur in every crinoid and comprise 
the ossicles represented in the early larva, the basals, the infrabasals, 
the various plates of the rays or arms, the orals, and the joints of the 
stem. The supplementary pieces, which make their appearance in the 
more advanced stages, but which are altogether unrepresented in some 
groups, comprise the remaining plates. The primary ossicles belong 
either to the “abactinal”’ or to the “actinal” system. Those of the 
former including all the plates, connected with the chambered organ 
and axial cords; the others comprising those communicating with the 
mouth and the annular vessels surrounding it. 
