DAC} LIVERPOOL BIOLOGICAL SOCIETY. 
plate are called ‘‘ portion of a band of elongated mesoder- 
mal cells found accompanying a skeleton fibre.” 
I have mentioned already the great similarity which 
exists in the external appearance of Axinella mammilluta 
and Polymastia mummillaris. As it might be misleading 
to distinguish the species by the spicules alone, as those 
of Avinella mammullata sometimes approach the tylostylote — 
character, and those of Folymastia mammullaris the tylote 
character, it appeared quite necessary to sectionize one of 
the papille for the sake of identification. The difference 
then is quite striking. In Polymastia mammillaris the 
papilla has the form of a tube with a large central cavity, 
with large subdermal spaces and well developed pore- 
membranes.* None of these characters are present in 
Avinella mammillata. Inside of the papillae we have here 
and there larger or smaller quite irregular cavities, no 
distinct subdermal spaces, and of oscula, pores and pore- 
membranes nothing definite could be seen. 
I found one specimen of this new species in one of the 
tidal pools on the north end of Puffin Island, at lowest 
tide, April, 1889. 
Raspailia ventilabrum, Bowerbank. 
Dictyocylindrus ventilabrum, Bowerbank. 
In my previous report I regarded this species as identi- 
cal with Raspazlia viminalis, Schmidt, and described it 
under that name. But, as pointed out recently by Top- 
sent,+ there exists a difference between /?. vimznalis, 8.,- 
and A. ventilabrum, B. The styli are slightly tylostyvlote 
in R. viminalis, whilst in R. ventilabrum they are of the 
normal character. 
* See my former Report in Proc. Liverpool Biol. Society, vol. iii., pl. vi., 
figs. 2 and 3. 
+ Emile Topsent, ‘‘ Etudes de Spongiaires.’ 
> 
Revue Biologique du Nord 
de la France, tome ii., no. 8, Mai, 1890. 
° 
