REPORT ON THE ALCYONARIA. 135 



prominences. These spicules measure, length by breadth, including the spiny combs — 

 0-58-0-16; 0-33-0-12; 0-22-0-13 ; 0-41-0-12 ; 0-3-0-12 mm. The spicules of the 

 deeper layers are spindles, sometimes with pointed, sometimes with truncated ends ; on 

 all sides armed with branching spines; their length by breadth being 075-0'12; 

 0"41-0-12; 0-45-0"01 mm. The darker violet layer contains straight or feel )ly bent 

 spindles, with simple spines, or blunt, somewhat rough spines, with a length by breadth 

 of 0'38-0"03 ; 0'2-0'03 mm. The axis is of a dark brown colour, horny, and somewhat 

 flattened and thickened at the commencement of tlie branches. The colour of the stem 

 is of a light brimstone. The deeper layer of the coenenchyma is of a violet hue. The 

 habit of the species and the form of the polyps agree very closely with Eunicea humilis, 

 Milne-Edwards,^ so that, being found in the same locality, the identity of the two is not 

 improbable. While fi'om the shape of the polyps and its habit the species might be 

 placed among the Eunicea ; yet the shape of the superficial layer of spindles, and the 

 absence of the outer club-shaped layer, characteristic of Eunicea, makes it more expedient 

 to place it among the Muricea ; where however it may be regarded as somewhat inter- 

 mediate between the two genera. 



Hahitat.—QSB&hia.; depth, 10 to 20 fathoms. 



Family V. P l e x a u m D^, Gray. 



Plexaiiridee, Gray; Ann. and Mag. Nat. Hist., ser. 3, vol. iv. p. 442, 1859. 

 Euniceidx, Kulliker, Icones Histiol., Abth. ii. p. 137, 1865. 

 Plexaiiridx, Yerrill, Trans. Connect. Acad., vol. i. p. 413, 1869. 



Professor H. Milne-Edwards (1857) arranged the genera Plexaura and Eunicea in a 

 division of his second group of the Gorgonacese with the genera Gorgonia and Lepto- 

 gorgia; following in close sequence of time Dr. Gray (loc. cit.) made the family 

 Plexauridse to include the two genera Plexaura and Etcnicea, indicating also two new 

 genera. 



This family he characterised as follows : — " Bark granular, persistent, cork-like, 

 without any impressed grooves. Cells placed equally on all sides of the branches." 



Kolliker {loc. cit.) adopted the genus Eunicea as the type genus, and diagnosed the 

 family Euniceidae as " having a thick coenenchyma, not supei-ficiaUy echinulate, but 

 provided with a cortical layer of club-shaped spicules ; verrucas absent or well developed. 

 Axis calcareous (Plexaurella) or horny." 



Kolliker included in this family Eunicea, Lamk., Plexaura, Lamx., pro parte, and a 

 new genus Plexaurella, for Gorgonia dichotoma, Esper, and allied forms, in which the 

 stem structure and spicules were of a diSerent type from those in Plexaura as now 

 defined. 



' Hist. Nat. des Coralliaires, vol. i. p. 149, pi. B^, fig. 1. 



