138 Mr. H. J. Carter on 



family for wliicli Dr. Gray has proposed the name of " Aphro- 

 cerasidpe," and which Hiickel has phieed among his Leucones, 

 as above stated. 



Are we, then, to distribute these species according to the 

 structm-e of the wall or according to their peculiar spiculation ? 

 for " peculiar" it is, since the acerate form that 1 have described 

 is not, to my knowledge, to be found in any other calcareous 

 sponges but the " Aphrocerasidaj." I must leave this for 

 future observation to decide, while for the present their 

 descriptions may remain where they are. 



It is possible that here and there one of the large acerates 

 may have a lanciform end or vary a little in its symmetrical 

 form ; but these are accidental occurrences. 



Here I might add that, as this form of acerate spicule is 

 identical with one which is very common among the non- 

 calcareous sponges, and the " Aphrocerasid^e " are the only 

 ones in which it occurs among the calcareous sponges of the 

 present day, so it may be assumed, in a fossil point of view, 

 as Zittel has done, that a calcareous sponge did exist in the 

 Cretaceous age, in which the only spicules were of this form, 

 that is without radiates ; and hence Zittel has instituted for 

 his third family of fossil calcareous sponges the name of 

 " Pharetrones," which, until this assumption can be proved, 

 must remain, as Prof. SoUas has described and illustrated it, 

 under the name of Pharetrospongia Straham, among the non- 

 calcareous sponges, or those possessing siliceous spicules of 

 this form alone (Quart. Journ. Geol. Soc. 1877, vol. xxxiii. 

 p. 242 &c. pL xi.). 



The next species that will be described, as hitherto it has 

 only been named, is of the same type as Aphrocei-as, but 

 possesses a form of the triradiate spicule which is so peculiar 

 that it has been actually identilied with one in a fossil calca- 

 reous sponge of Jurassic age, and is therefore also of much 

 palaeontological interest. It is that to which I have alluded 

 in my preliminary remarks under the name of Lelapia aus- 

 tralis (' Annals,' 1886, vol. xvii. p. 440). 



36. Lelapia australisj Gray. 



Lelapia ausfralis, Gray, Proc. Zool. Soc. 1867, p. 557. 



Individualized. Cylindrical, with enlarged free end bent 

 upon itself and elongated transversely, hammer-like. Colour 

 whitish yellow. Surface even, presenting a number of large 

 long acerates like those of the foregoing species, imbedded longi- 

 tudinally at variable distances apart, being more or less obscured 



