DENDY—REPORT ON THE CALCAREOUS SPONGES 3 
charged with peculiar yellow bodies, which doubtless accounts for the fact that it is much 
more opaque in appearance than the former. 
Both specimens are of the typical ‘“Clathrina” form, the ascon-tubes being very 
* slender and forming a very close-meshed reticulation, especially on the surface, which 
appears closely and minutely punctate from the presence of the very numerous pseudo- 
pores. It will be desirable to describe the two specimens separately, and they might even 
be considered as representing distinct varieties. 
cxx. 7. The reticulation of the ascon-tubes (Plate 1, fig. 1) is so close that the 
pseudopores are scarcely visible to the naked eye, and the whole colony appears at first 
sight to be enveloped in a continuous dermal membrane (pseudoderm). The entire sponge 
is about 25 mm. in greatest diameter by 15 mm. in height. It may be described as 
proliferously lobose ; the lobes lamellar, ascending and folded, varying greatly in size and 
shape, and occasionally bearing an open vent at the summit. The colour in alcohol is 
white and the texture soft and delicate. 
The canal system is of the reticulate type E*, without pseudogasters or pseudoscula, 
but the ascon-tubes in the middle of the lamellze form very wide gastral cavities (lined by 
collared cells) which open to the exterior through the vents. These central cavities are 
surrounded by a rather thin wall composed of the reticulation of smaller tubes, which open 
into them. 
The specimen is not in a good condition for histological examination, but there 
appears to have been a rather copious endogastric network of slender connective tissue 
threads, as in Leucosolenia proaima Dendy. The collared cells are in a somewhat 
elongated condition, with basal nuclei. Their transverse diameter at the base is about 
0-004 mm. and they line the gastral surfaces in a perfectly normal manner. 
The skeleton exhibits the normal arrangement and the spicules may be classified as 
follows :— 
(1) Hquiangular triradiates; with straight, fairly sharply pointed rays (Plate 3, 
fig. 1,a). These are of two principal sizes, (a) with rays measuring about 0°14 mm. in 
length by 0°012 mm. in thickness at the base, characteristic of the pseudoderm, (8) with 
rays about 0°074 by 0:007 mm., characteristic of the deeper parts of the sponge. 
(2) Quadriradiates (Plate 3, fig. 1, b), resembling the deep triradiates but with a 
very sharply pointed, perfectly straight apical ray, projecting into the gastral cavity at 
right angles to the three facial rays; length of apical ray about 0°05 mm., but variable. 
cexx. 11. The entire colony, a portion of which is represented in Plate 1, fig. 2, 
forms a dorsi-ventrally flattened crust, composed of low ridges and lobes and pierced by 
a few large holes which give it a coarsely clathrous character. The reticulation of the 
ascon-tubes on the surface is not quite so fine-meshed as in cxx. 7, so that the innumerable 
pseudopores are easily visible to the naked eye. The vents are minute and difficult to 
recognize, situated on low rounded eminences. ‘The entire sponge is some 40 mm. in 
maximum diameter, but not more than 3 or 4 mm. in height (thickness). The colour in 
spirit is light brown, apparently owing to the numerous yellow bodies which it contains. 
* Cf. Dendy [1891]. 
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