THE FOSSIL CRICOID GENUS DOLATOCEINUS AND ITS ALLIES. 6 



thoroughly distinct from the types with which they have been asso- 

 ciated. The following definition and brief discussion will be suffi- 

 cient for the present purpose: 



Family MELOCRINIDAE; section Dolatocrinites. 



Monocyclic. Lower brachials, with well-defined interbrachials, 

 forming part of the dorsal cup. Radials in contact all around. 

 Symmetry of dorsal cup but little, or not at all, disturbed by anal 

 structures; cup usually wider than high, broadly rounded below, 

 with base depressed, flattened, or concave. Arms usuallv simple; 

 biserial with few exceptions. 



ANALYSIS OF THE GENERA. 



Basals 4: 



Arms simple, biserial; base obconical; no auals Technocrinus. 



Arms branching, biserial both above and below the bifurca- 

 tions; base forming an inverted cone; no anals Clonocrini's. 



Basals 3, unequal, sometimes anchylosed; 



Calyx usually small, or of moderate to large size; iBr few, in not 

 over two ranges. 



Anal side not differentiated in dorsal cup. 



Dorsal cup low and wide; basals small, undivided, sunk 



in a shallow cavity; arms simple, uniserial Allocrinu.'=. 



Dorsal cup higher than tegmen, broadly rounded; base 

 usually flattened or concave. 

 Tegmen flat or low convex, nearly symmetrical, 

 mth subcentral anal tube. 

 Arms little known; probably biserial, and 

 simple, except in one species which should 

 go into another genus; openings 10 to 40. 

 Basals small; usually in a conical depres- 

 sion and anchylosed; the smaller one, 

 when distinguishable, in left anterior 

 position . 



IBr 2 DoLATOCRINUS. 



IBr 1 Stereocrin rs. 



Anal side slightly differentiated in the dorsal cup by an 

 extra plate in second range. 

 Dorsal ciip subcylindrical; basals large, divided; 



radials large, IBr small ; arms unknown Gentriocrinus. 



Anal side also strongly differentiated in the tegmen by a 

 series of large, ridge-like plates extending from the second 

 IBr range to base of anal tube. 



Dorsal cup low, broadly rounded, base flattened or 

 concave; basals usually divided. 



Tegmen exceeding dorsal cup in height, strongly 

 bulging posteriorly, but with subcentral anal 

 tube. 

 Arms uniserial, simple. 



Basals distinct; small basal in left posterior 

 position; IBr 2, the first reduced and 

 irregular in form CoMANTHocRmna, new genus. 



