Bibliographical Notice, 419 



siliceous sponges of the order Cornacuspongiae, Vosroaer, and these 

 are placed in the artijidal order Monoceratina, characterized by a 

 soft ground-substance or mesoderm, with a supporting skeleton of 

 spongin fibres, without proper spicules, but in some instances with 

 flesh-spicules (microsclera), and with pyriform or sac-shaped ciliated 

 chambers ; in other words, they are siliceous Cornacuspongiae, but 

 without skeletal or proper spicules in the sup^wrting skeleton, 

 though iu some instances still retaining minute flesh-spicules of 

 the same types as in the more typical siliceous sponges. The fourth 

 main group of horny sponges is a relatively small one ; and it is 

 considered as a natural order, allied to the siliceous Hexactinellida, 

 and from this it is named Hexaceratina. 



The first family of the artificial order Monoceratina, the Aulenidse, 

 includes but two genera, Aidena and Hi/attelhi, and in the former 

 of these the skeletal fibres are not only charged with sand-grains, so 

 common in the fibres of horny sponges, but they possess true eehi- 

 natiug siliceous spicules similar to those of the siliceous Desmaci- 

 donidae ; and the author acknowledges that the genusis placed with 

 horny sponges not because it properly belongs to this group, but 

 because it furnishes an interesting and important link between the 

 typical homy sponges and typical siliceous Desmacidonida?. 



The second family of the Monoceratina, the Spongida, is the 

 largest of the three groups, and, as defined by the author, contains 

 seventeeu genera. The sponges of this family are not clathriform ; 

 they have small spherical or pear-shaped ciliated chambers, '02 to 

 •05 millim. wide ; the ground-substance or mesoderm is granular 

 in varying degrees, and the horny fibres of the reticulating skeleton 

 may be solid or pithed, and, of course, destitute of proper sjiicules. 

 These sponges are regarded as very closely related to the siliceous 

 Chalinids, and in fact merely their modified descendants, which have 

 lost the ancestral spicules whilst retaining their external form and 

 appearanc3 for a protective purpose. It is significant to find that 

 the mere relation of the size of the ciliated chambers is adopted by 

 the author as a distinguishing feature, and in certain genera also 

 the dimensions of the fibres and the skeletal meshwork are regarded 

 as good generic characters. 



Within this family are embraced the sponges of commerce, 

 belonging to the genera Eusjwngia, Bronn, and Hippospongia, 

 Schulze. These genera are very closely allied and connected by 

 numerous transitional forms which run into each other at every 

 point, so that it is an almost impossible task to establish satisfactory 

 species or varieties ; but in spite of this the author finds it necessary 

 to make nine new forms in Eu^^pongia, bringing the number iu this 

 genus to thirtj'-one, and six new in IJippospon<jia, which now 

 numbers twent3'-sevea species and varieties. 



A full account is given of the peculiar filamentous bodies so 

 abundant iu the genus Hircinia, which have been the subject of very 

 varied opinions amongst spougologists, some considering them to be 

 parasitic organisms, others that they have been produced by the 

 sponge itself. Lendenfeld formerly held that they were foreign 

 organisms, Oscillarians, which multiplied in the sponge and becauie 



