432 Mr. H. J. Carter on 



kindly sent me, it is stated that the ampullaceous sacs (Geis- 

 selkammern), which have a peculiar elongated sha])e and are 

 placed side hj side, with their apertures directed towards the 

 centre of the exhalant canal, like the radial chambers of 

 Grantia ciliata around its cloaca, average " about 100 /i " in 

 length and " about 60 yu, " in breadth ; while those which he 

 had previously described and illustrated in Spongelia (Zeit- 

 schrift f. wiss. Zoologie, Bd. xxxii. p. 134, Taf. viii. fig. 5) 

 are stated to have averaged "von 0"06-0"l mm." in diameter. 

 The radial chambers of Grantia ciliata vary of course with 

 the size of the specimen, but may be l-24th in. long by l-60th 

 in. in diameter and even more, that is about 1'0159 by '5079 

 millim., so that there is a great difference in size between the 

 ampullaceous sac of Euplectella aspergiUum and its apparent 

 analogue in Grantia ciliata^ however much in other respects 

 they may resemble each other. 



As there are no specimens of the order Hexactinellida in 

 Mr. Wilson's collections, let us pass on to the next, viz. the 

 Caicarea, wherein will be included not only the specimens 

 which came " from the neighbourhood of Port Phillip Heads," 

 but those also which were subsequently obtained by 

 Mr. Wilson from " Western Port," about 15 miles to the 

 westward. 



Order VITI. CALCAREA. 



Here I cannot premise as heretofore any classificatory 

 arrangement of the species of this order, as I had not studied 

 them sufficiently for this purpose when my Classification of 

 the Spongida generally was published (' x\nnals,' I. c.) ; and 

 not having done much more since in this way I must still, as 

 I did then, recommend the student to study Hackel's work 

 entitled ' Die Kalkschwamme ' (eine Monographic in zvvei 

 Banden Text und einem Atlas mit 60 Tafeln Abbildungen, 

 1872), to which, however, I must now add the judicious 

 criticism on this work of Dr. N. PolfejaefF, in his " Report on 

 the Caicarea collected by the ' Challenger ' Expedition " 

 ('Challenger' Reports, Zoology, vol. viii. pt. xxiv. 1883), 

 and his proposed alterations, throughout which he has not 

 forgotten the respect due to Hackel nor the advantage he has 

 derived from that first and brilliant step into this field of 

 inquiry which Hackel has put forth in ' Die Kalkschwamme.' 

 Doubtless there are shortcomings in every man's work, and 

 thus every man's work helps primarily to supply them ; hence, 

 as Dr. Polejaeff properly remarks, " every one is son of his 

 time" (Report, p. 6). 



