128 ARTHUR DENDY. 
nesses of a similar nature I desire to express my most sincere 
thanks to Mr. Carter. The material was fortunately in suffi- 
ciently good condition to enable me to make out the structure 
of the canal system, and to establish the correctness of my sup- 
position that it belonged to the Leuconoid type. By far the 
most interesting feature of the species, however, proved to 
be the very remarkable reticulated fibrous character of the 
skeleton, which appears to have hitherto escaped observation. 
This character is unknown in any other living calcareous 
sponge, while it forms the most prominent feature in the great 
fossil group “‘ Pharetrones”’ of Zittel (3), hitherto regarded as 
entirely extinct. Lelapia australis may therefore be looked 
upon as the only known living representative of this important 
group,! and a minute study of its anatomy thus acquires an 
exceptional interest. 
I have much pleasure in again expressing my most sincere 
thanks to Professor G. B. Howes for kindly undertaking the 
correction of the proof sheets in my absence from England. 
II. Anatomy or LELAPIA AUSTRALIS. 
A. External Form. 
The larger of the two specimens (fig. 1) measured 3} inches 
in length by 1 inch in greatest diameter, and is thus described 
by Mr. Carter (2, p. 148) :—‘ Cylindrical, clavate, the largest 
part upwards, somewhat curved or bent upon itself, rugose 
longitudinally. Consistence firm. Colour dark grey. Surface 
even, smooth, interrupted by the projection of crooked ridges 
extending from the free to the fixed end, subspirally and longi- 
tudinally, in broken lengths, sometimes reduced to mere scat- 
tered tubercular points, most pronounced on the concave side 
towards the mouth, least so on the opposite side: largest and 
most continuous ridge + inch long, ;4 inch broad, and 3; 
3 
inch high. Pores plentifully scattered over the surface, not 
1 Whether the group, as it stands, is a natural one, appears to me 
doubtful. 
