668 EXPlANATIOir 01' THE PLATES. 



[D' shows the naked calcareous axis of one of its branches.] 

 D". Portion of D', x 6. Prom Port Molle. 

 Pig. E. Acaharia serrata. Portion of larger specimen in spirit, nat. 

 size. E'. Portion of second joint above first bifurcation, 

 of same specimen, from Port Darwin, 7-12 fms., X 6. 

 P. Iciligorgia orientalis. Type specimen, in spirit, reduced to 

 one half nat. size. P'. Portion of left-hand branch, the 

 margin as seen from the side, showing the depressions for 

 the zooids and the common groove which contains them, 

 X 2. P", Portion of main stem just below bifurcation, 

 from front, showing four exsert zooids. Prom Torres Straits, 

 10 fms. 



Plate XXXVIII. 



Fig. a. Mopsella clavigera, cortical clavate, a', cortical bifurcate, 

 and a'' & a'", Blattkeule spicules, x 100. 



J. Melitodes albitincta, fusiform, and 6' , small nodular cortical 

 spicules, xlOO. 



c. AccAaria serrata, long, and c', short verruca-spicules ; e", 



short, and c'", long cortical fusiform spicules. All x 150. 



d. Echinom/urieea indo-malaccensis, d & d', chief forms of the 



toothed spicule of the verruca, d" & d'", cortical spicules. 

 All x70. 



e. Iciligorgia orientalis. Chief forms of spicules, X 70. 



f. Psilacaharia graciUima, cortical, f & f"', verruca-spicules, 



X 70. [The ridged cortical spicule has been omitted.] 



g. Pleonaura prodonga, var. typica, radiate, and g', Blatt- 



keule cortical spicules, x 70. 



h. Plecoaura prcelonga, var. dnerea, Blattkeule cortical spicule, 

 X70. 



SPONGES. 



Plate XXXIX. 



Pig. A. Stelispongm eoccavatus. Type specimen (dry) from Arafura 

 Sea. Eeduced to one half nat. size. 



