STUDIES ON THE COMPARATIVE ANATOMY OF SPONGES. 237 



examples are given in my synopsis of the Australian Calcarea 

 Heterocoela (4). 



Genus 11. — Lelapia (Gray [18], emend.). 



Diagnosis. — Canal system unknown. Skeleton of the 

 chamber layer composed of large, longitudinally arranged 

 oxea, crossed at right angles by bundles of tuning-fork shaped 

 triradiates whose basal rays are directed towards the dermal 

 surface. 



Remarks. — This genus was first proposed by Gray (18) for 

 certain remarkable tuning-fork shaped spicules described by 

 Bowerbank, but the sponge to which those spicules belonged 

 was then unknown. Carter (12) subsequently described some 

 sponges, collected by Mr. J. Bracebridge Wilson in the neigh- 

 bourhood of Port Phillip Heads, in which similar tuning-fork 

 shaped spicules were present, and he gave to these sponges 

 Gray^s name, Lelapia australis. Whether Mr. Carter's 

 species is really identical with the sponge to which the spicules 

 described by Bowerbank and Gray belonged, must remain an 

 open question. The fact that the spicules in question came 

 from Australia lends an air of probability to the identification, 

 but then similar spicules are known in the fossil condition 

 from deposits as old as the Cretaceans, according to Carter 

 (12). In any case, the Victorian sponges described by Carter 

 (12) under the name Lelapia australis must stand as the 

 types of that species, and the species thus constituted must 

 stand as the type of the existing genus Lelapia, 



Unfortunately we know nothing definite as to the canal 

 system of Lelapia australis, although it is to be inferred, 

 from the fact that Mr. Carter places it amongst the '^Leucones,^^ 

 that the canal system belongs to the Leuconoid type. The 

 structure of the skeleton as described by Mr. Carter is very 

 peculiar, and it is upon this character alone that the generic 

 diagnosis must, for the present, be based. 



The position of the genus in the system of classification is 

 necessarily only provisional; and it can only be finally deter- 

 mined by further research on the canal system. Unfortunately 



