24 



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 fci-m, however, 

 may bo taken into consideration, and the regular and azygous 

 areas dependent thereon as controlling th(^ form, and also the 

 surface ornamentation, especially wIhtp it inchides the presence 

 or absence of radial ridges, and tlie.se particulars may be of 

 speciH • importance. But to place these si)ecics in a familj' 

 distinct from the Actinocrinidir is without any warrant so far 

 as any learning has extcndi'd. 



AGAKICOCKINUS ADAMSENSIS. n. sp. 



Plate I, Fig. 7, dziji/oits side rieic: Fit]. S, sidiniiit vieic; Fit;. 



0, hnsal view. 



Species medium or above nuMlium size. Calyx nearly flat, 

 though slightly convex about the basals and first radials. Out- 

 line subpentagonal. Plates thick, moi'e or less (•on\ex. and 

 part of them subs])in()ns. Arm ujicnings directed rather belo^^ 

 a horizontal line. 



basals form an hexagonal disc, very little widei- than the 

 diameter of the column, that contains a hemispherical depress- 

 sion foi- the attachment of the column. Colnmnar canal quite 

 snuill. The first i)rimaiy radials are lai'ge. rather wider than 

 long, three hexagonal and two heptagonal. All of them ai'e 

 sculptured so as to be pyramidal or s\ibspinous. the apices ex- 

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

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

 jilate. Second primary I'adials short. (|uadrangular, four or live 

 times as wide as long. Tliird [irimary radials about one-half 

 larger than the second, ]jenta.gonal. axillai-y, and in three of 

 the rays support on each upper sloping side two secondary 

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

 distal sidi' of encli tliii-il |)rim;ir\- i-:iili:il ail joinin'j' tlie azygons 



