134 Dr. J. E. Gray on some 



Prof. Owen has said that among the ]\Iarsupials " the Koala 

 has the best clami to typical preeminence " (Todd's Cyclop. 

 vol. iii. p. 329) ; and certainly from the foregoing accomit it 

 will be seen that this animal presents, in its muscular system, 

 a greater number of structural divergences from the general 

 placental type than, perhaps, any other Didelphian. 



XX. — On a neio Genus of Hexaradiate and other Sponges 

 discovered in the Philippine Islands hy Dr. A. B. Meyer. 

 By Dr. J. E. Gray, F.K.S. &c. 



Dr. Adolf Beenhard Meyer has brought with him som^e 

 beautiful species of hexaradiate sponges, which he obtained 

 at Talisay on Cebu, in March 1872, and they are now in the 

 collection of the British Museum. 



The two principal sponges discovered by Dr. Meyer would 

 form two very distinct families according to the classification 

 published in the Ann. & Mag. Nat. Hist. 1872, June, p. 442. 

 They both belong to the order Coralliospongia. Before I pro- 

 ceed to define them I may remark that the order may be 

 divided into three groups : — 



I. The normal Coralliosponges have elongate subulate rays 

 to the hexaradiate spicules, Avhich are generally smooth , but 

 one or more of them may be covered with spines or lobes 

 directed tOAvards the tip. This group contains the first ten 

 families in the paper above referred to. The genus Cratero- 

 morpha here described appears to belong to it. 



II. This group, which may be considered the abnormal 

 form of the order, has the hexaradiate sjnnes with short uni- 

 form rays of equal length, each ending in a number of re- 

 fiexed lobes, and forming in their completely developed state 

 a cube. 



It will contain two families, and may be thus divided : — 



A. Sponge sessile^ attached. 

 Fam. 1. Carteriadas. 



B. Sponge free^ attached to the hottorn of the sea hg tufts of 

 elongate anchoring fhres, 



Fam. 2. Meyerinidse. 



Sponge elongate, tubular, covered with a cobweb-like netted 

 coat, with a circle of tults of anchoring fibres at the base, wliich 

 extend more than halfway through the length of the body, and 



