sixteen arms, and another may have three arms in each of two 

 rays, and four arms in each of two rays, and two arms in the 

 other, making sixteen arms. In such case the two specimens 

 will belong to different species. It will be apparent that the 

 changes, in the latter respect, may be very numerous in spec- 

 imens having sixteen or more arms, and we find, in fact, that 

 such is the case. It will be seen that these changes alone will 

 provide for more species than have been described. These are 

 therefore, fundamental variations. The general form, however, 

 may be taken into consideration, and the regular and azygous 

 areas dependent thereon as controlling the form, and also the 

 surface ornamentation, especially where it includes the presence 

 or absence of radial ridges, and these particulars may be of 

 specific importance. But to place these species in a family 

 distinct from the Actinocrinidm i-s without, any warrant so far 

 as any learning has extended. 



AGARICOCRINUS ADAMSENSIS, 11. Sp. 



Plate I, Fig. 7, azygous side view; Fig. 8, summit vieiv; Fig. 



.9, basal view. 



Species medium or above medium size. Calyx nearly flat, 

 1 hough slightly convex about the basals and first radials. Out 

 line subpentagonal. Plates thick, more or Jess convex, and 

 part of them subspinous. Arm openings directed rather below 

 a horizontal line. 



Basals form an hexagonal disc, very little wider than the 

 diameter of the column, that contains a hemispherical depress- 

 sion for the attachment of the column. Columnar canal quite 

 small. The first primary radials are large, rather wider than 

 long; three hexagonal and two heptagonal. All of them are 

 sculptured so as to be pyramidal or subspinous, the apices ex- 

 tending below the basals, so that a specimen laid upon a fable 

 will rest upon these plates and the point of the first azygous 

 plate. Second primary radials short, quadrangular, four or five 

 times as wide as long. Third primary radials about one-half 

 larger than the second, pentagonal, axillary, and in three of 

 the rays support on each upper sloping side two secondaiy 

 radials, which gives to each of these rays two arms. On the 

 distal side of each third primary radial adjoining the azygous 



