8 Porifera. C. Porifera calcaria. 



The Ceratina are altogether an old group and their supposed close relation to, 

 say, Chalinidae is to be given up. 



. Haeckel describes several quite new 'deep-sea Keratosa', belonging to the 

 Spongelidae, and new groups. He erects two orders, Cannocoela ( tubular 

 canal-system, on the Asconal-type ) and Domatocoela (vesicular canal- 

 system, on the Leuconal-type, with large flagello chambers*). The former contains 

 only one family, Ammoconidae: Keratosa without spougiu-fibres. Pseudo- 

 skeleton composed of xenophya (= manifold foreign bodies) , which are disposed 

 in the thin malthar plate of the porous tubular body. Ammosoletiia, Ammolynthus, 

 and Ammoconia. The thin wall is pierced by simple pores through which the 

 water enters into the simple gastral cavity. Remains of the entodermal flagellated 

 epithelium lining the inside of the tubes were visible in two genera, but no trace 

 of an exodermal pavement-epithelium was seen. The main mass of the thin wall 

 is formed by foreign bodies. They are united by a homogeneous ground-sub- 

 stance ( maltha ), in which the small cells of the connective tissue are recognisable. 

 The Domatocoela are divided into three families: 1. Psamminidae. Kera- 

 tosa without spongin-fibres. Pseudoskeleton composed of foreign bodies, cemented 

 together by maltha. Psammina n., Holopsamma Crtr., Psammopemma Marsh. 

 2. Spongelidae. Keratosa with a reticular horny skeleton, which encloses 

 foreign bodies. Maltha transparent, not granular. Two deep-sea genera: 

 Cerelasman., Psammophyllum n. 3. Stannomidae. Keratosa with a fibrillar 

 spongiu-skeleton composed of thin, simple or branched, spongin-fibrillae, never 

 anastomosing or reticulated. Pseudo-skeleton composed of foreign bodies. Three 

 deep-sea genera : Stannophyllum n., Stannarium n. , Stannoma n. - - The majority of 

 the deep-sea Keratosa live in symbiosis with Hydroids [cf. infra, Coelenterates, p 6] . 

 Dendy ( 3 ) studied the anatomy of Stelospongus flabelliformis Crtr. The 

 skeleton is composed of a rather irregular reticulation of cylindrical, slender, 

 horny fibres, branching and anastomosing freely. The meshes are wide. The 

 inhalant apertures are scattered all over the depressed areas on the surface of 

 the sponge. These large areas are themselves subdivided into a great number of 

 smaller areas which appear to be strictly comparable to the pore-sieves of Phakel- 

 lia ventilabrum O.S. Through the pores the water enters into subdermal cavities, 

 which lead into large channels, comparable to the subcortial crypts, described 

 by Sollas in the Tetractinellida. The canal-system approaches Vosmaers third 

 type, though with transitions to the fourth, as in, e.g., Euspongia. The ecto- 

 some forms a thin layer; it is hard and tough, strengthened by a large amount 

 of sand. The membrane uniting the collar-cells, as described by Sollas and 

 Bidder independently from each other [cf. Bericht f. 1888 Porif. p 2 and 4], 

 finds a strong advocate in D., wo describes it in S. as beyond the possibility of 

 a doubt. The author proposes to call this Sollas' membrane. Lendenfeld ( 5 ) 

 has seen something of this kind. However, he does not consider it a membrane, 

 but believes that the flagellated chambers lie imbedded in the ground-substance 

 of the sponge, instead of resting on it, as hitherto supposed. 



Dendy ( 3 ) describes and illustrates a few points in the development of Stelo- 

 spongusjlabellifonnis Crtr. Ova and embryos lie in capsules, which possess proper 

 walls, lined internally by very large cells, which are probably nutritive. 



C. Porifera calcaria. 



See, supra p 4, Haeckel. 



Hinde describes a new fossil Calcisponge, Leucandra walfordi, from the Middle- 

 Lias of Northamptonshire. 



