ALCrONAEIA. 361 



4-6 fms., bottom rock and sand. Studer's species was obtained at 

 Dirk Hartog Island, West Australia. 



06s. Three young, one older fresh specimen in spirit, one large adult 

 dry, and one large adult dead and blackened specimen, and numerous 

 fresh fragments dry and in spirit represent the species. The largest 

 specimen, which has lost its terminal twigs, measures 400 millim. in 

 height by 275 in maximum breadth. 



This well-marked species is very well represented in the collection 

 by specimens showing difEerences due to age and other causes, 

 constituting variations of no inconsiderable extent. The internodes 

 of none of the branches, except the few primary divisions of the base, 

 attain a greater lateral diameter than 2^ millim. or a greater antero- 

 posterior one than 3g millim. ; it is further distinguished by the 

 constant club-shaped character of the stouter fusiform tuberculate 

 spicules of the general cortex and by the oblong transverse section of 

 the internodes. 



The tendency to vary in colour is very remarkable ; the axis of the 

 joints ranges from white to brick-red, that of the internodes from 

 white to crimson. The pink colour of the internode-axes is ex- ' 

 hibited by all the young specimens and lost externally in most of 

 the adult colonies; but these generally exhibit a trace of their 

 earlier condition by the pink tint of the centre of the hard joint, as 

 may be seen by breaking it across ; on the other hand, the colour 

 may persist in its fullest intensity in the adult, as is shown by a 

 fragment of a good-sized specimen which occurs with crimson inter- 

 nodes. The dependence of the amount of anastomosis on the age of 

 the specimen is another very interesting feature of the species. Of 

 the two youngest complete specimens (one 40 miUim., the other 

 upwards of 50 millim. long), one has but one case of anastomosis 

 among its numerous branches, while the other has seven such 

 cases. 



ACABAEIA. 



Gray, Ann. 8r Mag. K IT. (4) ii. p. 444. 



This genus has the general habit of Mopsella (viz. slender stem 

 and branches, the latter given off at acute angles), but has fusiform 

 instead of Blattkeule spicules in the cortex, replacing the small 

 nodular spicules of Melitodes. ^ 



35. Acabaria japonica. 



Mopsella japonica, Verrill, Proc. Ess. Inst. iv. p. 199, vi. p. 80. 

 PMelitsea tenella, Dana, U. 8. Expl. Exp. Zooph. p. 683. 



A fine dry specimen which I cannot distinguish specifically from 

 the above species ; it measures about 110 millim. in extreme vertical 

 and 30 millim. in extreme lateral extent. 



The terminal branches have the extremely slight thickness of 

 •5 millim. (excluding verruoae) ; the colour of the general cortex is 

 pale scarlet, that of the verrucee, which are prominent and rounded. 



