ALCYON'AKI \. 339 



present species. In habit these three species are closely similar. 

 A specimen in the Museum, which is apparently the typo of Bovella 

 ramulosa, Gray (Ann. & Mag. Xat. Hist. (4) v. p. 497), is closely 

 allied to E.jlabdlum, and should stand as Echinogorgia ramulosa. 



EuNICEACEJE. 



13. Plexaura prselonga, sp. n., var. typica. (Plate XXXVI. fig. F, 

 and Plate XXXVIII. figs, g, g'.) 



Growth upright, approximately in one plane. Common stem ex- 

 tremely short. Branching dichotomous ; branches few, almost 

 straight ; terminal branches lot) millim. ((5 inches) and upwards in 

 length in adult specimens. Stem and branches cylindrical, either 

 nearly of the same diameter throughout in both cases, viz. about 

 2-5 millim., or ranging from G millim. at base to 3 millim. at end of 

 branches in adult specimens. Cortex approximately smooth, even, 

 rather friable. Colour in dry state pale red-brown or dark tawny 

 brown. Verruca) small, not projecting from surface, equally distri- 

 buted over all parts, 5 to 1 millim. apart. Axis tough, flexible, 

 black. Cortical spicules : — (i.) Long fusiform, approximately straight, 

 tapering to sharp points, with few, scattered, tapering, sharp, simple 

 tubercles; size about -35 by -07 millim. (ii.) Stout fusiform-cylin- 

 drical, covered with low, blunt, compound tubercles ; size about *3 by 

 1 millim. (iii.) Irregular tri- to sexradiate, arms cylindrical, taper- 

 ing to sharp points, with numerous but distinct, prominent, simple 

 or compound, pointed tubercles ; maximum diameter of spicule *25 

 to "52 millim., thickness of arms -042 to *1 millim. (iv.) Blattkeule ; 

 shaft with one or two distinct arms uniting in a moderately stout 

 neck, often themselves bearing secondary arms ; the whole shaft is 

 covered densely with very prominent, tapering, compound tubercles. 

 Foliar portion flattened in one plane, variable, either approximately ob- 

 long with rounded angles, or much drawn out laterally, forming angles 

 at this point, and with a point below, or with the lower edge broken 

 up into small lobes ; edges sharp, minutely scalloped. From the 

 shaft descend on to the foliar portion, sometimes more than halfway 

 down its face, one or more narrow, more or less prominent ridges, 

 tapering so as gradually to disappear ; or the place of each ridge is 

 taken by one or more rounded prominences ; both ridges and pro- 

 minences are smooth ; length of spicule about o millim., breadth of 

 Blatt -3 millim. 



Hab. Port Curtis, 5-11 fms., bottom sand and shells ; Port Deni- 

 son, 4 fms., bottom rock. 



Obs. Two dry specimens, the one from which the larger external 

 measurements were taken being largely decorticated, occur, also 



Plexaura may be open to doubt ; in its spicubition it agrees with Plexaurella as 

 limited by Verrill (Proc. Ess. Inst. vi. p. 42) ; but Dr. Klunzinger does not 

 state explicitly whether the axis is simply horny or whether it contains the 

 carbonate of lime, by the presence of which Kolliker distinguishes the genus 

 from Plexaura. 



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