Simpson — A Revision of the GorgonelliJae. 281 



in the different parts of the colony. Tlie verrucae themselves vary in shape 

 and size according to .the stage of retraction and also according to their 

 position in the colony. They may l)e elongated and conical, wart-like, or even 

 depressed below the surface of the coenenchyma. The axis is composed of 

 concentric laminae impregnated with lime ; the surface is marked liy 

 longitudinal ridges and furrows; but the number of these diminishes towards 

 the tip of the colony. The spicules contain " double-clubs," but neither 

 " clubs" nor extremely long " double-spindles " or " spindles." 



Genus Nicella emend. 

 The colony may be simple, slightly branched, dichotomously branched 

 or variously branched, with frequent anastomoses in one plane. The 

 coenenchyma is thin and finely granular ; the surface presents an arenaceous 

 appearance. The polyps are disposed in longitudinal series which alternate 

 with, and correspond in number with, the main longitudinal canals. In the 

 species so far known there are two main longitudinal canals. The number of 

 rows in any series varies according to the position in the colony ; and in the 

 older parts the polyps may encroach on the bare tracts so as to almost 

 obliterate them. The verrucae vary in shape and size according to the stage 

 of retraction ; when expanded they stand usually at right angles to the stem 

 and are terminally truncated ; when f uUy retracted they are low and conical 

 or dome-like ; intermediate stages always occur. The axis is composed of 

 concentric laminae, and is densely calcareous ; it is typically Gorgonellid in 

 character. The spicules consist of small double-clubs and slightly elongated 

 double-clubs, but characteristic are elmyjated dmiUe-spindles and spindles. 

 These latter types are quite distinct, and there are no intermediate forms 

 linking the two sets — i.e. double-clubs and spindles — together. They are also 

 usually large in most species. 



IX. — Genus Juncella emend. 

 A historical review of this genus has already been given, and also an 

 emended diagnosis. In the restricted emended sense — i.e. those Qorgonellids 

 whose spicules include " clubs " — the following species must be taken into 

 consideration : — 



1. Juncella j'uncea Pallas. 



2. Juncella fragilis Eidley. 



3. Juncella flexilis Studer. 



4. Juncella harhademis^ Wiight and Studer. 



' It is extiemely doubtful whether the Bpecimen identified by Wright and Studer as /. barba- 



densis is the same as the original specimen of that name, so that it has been considered advisable to 

 keep them separate. The " Chalk-Mger " /. bariadeiisis is a Juncella ; the original may not be. 



[2P2] 



