46 
Fig. 
bo 
LIVERPOOL BIOLOGICAL SOCIETY. 
EXPLANATION OF THE PLATES. 
Bladder cells. 0. Aya: 
Choanosome. os. Osculum. 
Ciliated chambers. p. Pores. 
Ectosome. p.m. Pore membrane. 
. Longitudinal bundles of spicules in transy. section. 
PLATE V. 
Raspailia stelligera, S., nat. size. 
. Raspailia viminalis, §., nat. size. 
a.,b.and c. Stylote spicules of Raspailia viminalis, 
S. (x 55). d. Spined spicule of the same (Xx 235). 
Portion of a transverse section through the middle 
of the stem of Raspailia viminalis (x 40). 
PEATE Vi, 
Tylostylote spicules of Polymastia mammuillaris. 
Gal X00) 3 b2-O6 285). 
Transverse section through one of the papille of 
Polymastia mamnullaris (Xx 100). 
Longitudinal section through one of the papillee of 
Polymastia mammillaris (X 60). 
Prate VII. 
. Vertical section through Sevriola compacta, n. sp. 
(x 100). [N.B. The third cladus of every triena 
has been left out as standing nearly at right angles 
to the plane of the section. ] 
. Microscleres of Setriola compacta, n.sp. a. (X 1000); 
b. (x 1000); ¢. (500). 
. The cladome of a dichotrizena of Sezriola compacta, 
n. sp. (X 200). [N.B. The rhabdome must be 
imagined as standing vertically upon the centre of 
the cladome. | 
