260 EDWARD A. MINCHIN. 
doubted that the osculum and gastral cavity of Ascetta are 
such. But it is a far cry from Leucosolenia to Euplec- 
tella, and no amount of similarity in structural relations will 
again from the upper surface,” and so on (Schulze, ‘ Mon. of Hexact.,’ pp. 21, 
22). What then must be our astonishment, after reading these words, to 
find Von Lendenfeld, in his ‘Monograph of the Horny Sponges,’ quietly 
putting down the gastral cavities of Hexactinellids as preoscular spaces, or 
even as pseudoscular, a name which he applies to entrances to the inhalent 
system (l. c., p. 739)! “In the tubular Huplectella aspergillum 
and in allied forms the central cavity, considering the wall of such a tube 
homologous to the lamella of the cup-shaped or irregular flattened forms, 
appears as a preoscular tube, so that here also there are no proper exhalent 
canals [I must confess to finding some difficulty in understanding this con- 
clusion]. Thus, roughly speaking, all Hexactinellids are lamelle, and the 
exhalent canal system is represented by a continuous cavity pervaded by 
lamelle. The chambers open into one side of it, and the oscula are situated 
in the opposite wall” (l.c., p. 717). And this from an author who can only 
have obtained such knowledge of the Hexactinellids as he possesses fromm 
reading Schulze’s monograph, and who has not a particle of evidence to 
support his view! nor, indeed, does he attempt to give us any. One more 
instance of Dr. von Lendenfeld’s homologies may well be discussed here, 
since it concerns the oscular sieve-plate. On p. 720 of his monograph of the 
‘Horny Sponges’ we find it stated in the description of Dendrilla 
cavernosa that “the terminal parts—pseudoscula—are covered over by 
fine sieves with circular pores 0°2 mm. wide, which can be entirely closed at 
the will of the sponge;” and on p. 758 of the same work we find that Dr. 
von Lendenfeld “ does not hesitate to compare it [‘‘ the cribriform membrane 
which is stretched over the wide terminal pseudoscula of Dendrilla 
cavernosa ” | directly to the terminal sieve of Euplectella aspergillum.” 
This sounds very well; but if we now turn to the more detailed description 
of this sieve in Dendrilla cavernosa given in Dr. von Lendenfeld’s 
“Studies on Sponges and the Vestibule of Dendrilla cavernosa” 
(‘ Proc. Linn. Soc. New South Wales,’ vol. x, 1886, pp. 557—561), we learn 
that “the cavity covered by the pore sieve is a pseudogaster, no oscula are 
found in its surface; it is a vestibule belonging to the inhalent system” 
(p. 557). Consequently the gastral cavity of Euplectella belongs to the 
inhalent canal system; but the chambers of Euplectella open, directly or 
indirectly, towards this gastral cavity, which leads to the astounding result 
that the chambers of Euplectella are turned the wrong way! A new kind of 
inversion of the layers! I am sure it is quite unnecessary to comment further 
on these fantastic and utterly groundless theories, or to point out the flagrant 
contradictions in which this author lands himself. 
