114 Proceedings of the Royal Irish Academy. 



{b) Smaller double-clubs, with a longer constriction, with more open heads, 



and with the warts less symmetrically arranged : 0'06 X O'Oo-i ; 



0-05 X -031 ; 0-049 x 0-0:27. 

 (c) Elongated double-clubs, tending towards double-spindles, with rounded 



blunt ends: 0-091 X 0-038 ; 0-0S7 X 0-03-1 ; 0-083 X 0-03-i. 

 {d) Elongated double-spindles, with pointed ends, and with a definite 



constriction: 0-118 x 0-03-4; 0-114 x 0-31; 0-114 x 0-023; 



0-103 X 0-023. 

 (e) Long spindles with a hint of constriction: 0-125 X 023; 



0-114 X 0-031. 

 (/) Shorter spindles also with a hint of constriction: 0-095 x 0019; 



0-087 X 0-015; 0-016 x 0-023. 



We have little hesitation in defining («;, (&), and (c) as distinct types ; 

 but it is just possible that (/) might develop into (c) or (d) according as 

 increase with growth was greater in length or in breadth. So many of each 

 kind occur, however, that we feel justified in defining them as separate for 

 the present, at any rate, until more is known with regard to their growth. 



The colour of the coenenchyma is a bright orange-red — but the tips of 

 the verrucae are more reddish. 



Zocaliti/. — Laccadives, 30-40 fathoms. 



Diagnosis, colony simple ; spicules contain double-clubs and double- 

 spindles, with transitions to spindles. The coenenchyma is thin, and 

 contains fotir main longitudinal canals. The verrucae are disposed in four 

 definite longitudinal series, separated by four bare tracts, which correspond 

 in position to the four main canals. The colony is markedly square in section. 



XXXI. Genus Nicella emend. 

 (a) Discussion of the Genus. 



This genus was established by Gray in 1870 (Cat. Lith. Brit. JIus., p. 40) 

 in the following terms : — 



Coral fan-like, in one plane, branched ; branches forked, rather diverg- 

 ing. Bark smooth, brown. Polyp cells cylindrical, truncated, diverging 

 from the stem at nearly right angles , mouth open. Axis calcareous, white 

 solid. 



To this genus he refers a specimen under the name Kicclla mauritiana, 

 and gives as a synonym his previous Scirpcaria dicliotoma (P.Z.S., 1859, 481-2). 



Kidley (xxix., p. 130) identified a specimen from Mauritius under the 

 name Nicella dichotoma, and made the following observation on the spicules : 

 "There is a dense cortical layer of small double-heads and a subjacent 



