and two Esperiadgeyy-o?>i the West Indies. 271 



conies from the coast of Caracas (Grundz. Spong. Faun. Atlant. 

 Geb. 1870, p. 60) ; but no figured illustration of this is given. 

 It is marked by Schmidt " nova species,'" yet appears to have 

 been figured by Dr. Bowerbank in the ' Philosophical Trans- 

 actions ' of 1862 (pi. 30. fig. 7), and called Ectyon sjmrsus by 

 Dr. Gray in 1867 ; so Schmidt's name of 1870 for this sponge 

 is not wanted. 



In Dr. Bowerbank's ' Monograph ' it is given as a type 

 specimen of his genus Oplilitaspongia (ottXit?;?, armed^), 

 wherein the spicules are confined to the external surface of the 

 kerataceous fibre, " exterspiculate " (externo-spiculate ?) , in 

 contradistinction to the foregoing genus ChaJina, where the 

 spicules are entirely " interspiculate " (introspiculate?), illus- 

 trated in the type specimen Chalina oculata, fig. 262. 



Nothing can be more natural or more distinct than these 

 two characters for these two kinds of sponges respectively ; 

 yet, immediately after making the distinction, Dr. Bowerbank 

 calls one of the commonest opalitous sponges on this coast 

 {Halichondria seriata, 3 ohw^ion) " Chalina seriata^^ (fig. 287), 

 thus upsetting the ocular demonstration by mitrustworthy 

 mental reflection. 



Schmidt, too, because the tricurvate or bow-like spicule is 

 present in this sponge, would place it among his Desmacidinae 

 (Atlant. Spong. Faun. p. 76, note, & p. 77), when it would 

 come, together wnth Dr. Gray's Esperiad^e, in his second sub- 

 section, viz. Spiculospongiffi, perhaps near Dictyocylindrus 

 (p. 519, I. c.) ; but Dr. Gray has more properly putnt with his 

 Ophistospongi^e (Ophlitaspongia, Bk.), in his first subsection 

 under the second order of Keratospongi®, or horny sponges, 

 with the name of Seriatula seriata (p. 515, I. c). I say " more 

 properly," because it is much more horny than spiculous or 

 siliceous, which is the opposite to the Desmacidin^. 



Perhaps the most useful primary division of the Spongiadje 

 may be based on the rigidity or supporting-power of the 

 skeleton-structure, ^'. e. in short, on the skeleton, thus : — 



1. The rigidity of the skeleton dependent on a predomi- 

 nance of the sarcodal over the siliceous element. Com- 

 mencing with Verongia, Bk., in which there is nothing but 

 homy fibre. 



'2. The rigidity of the skeleton dependent on a predomi- 

 nance of the siliceous over the sarcodal element. Ex. gr. 

 Dactylocalyx ijumiceus, Stutchbmy, in which the horny fibre 

 is silicified. 



3. The rigidity of the skeleton dependent on a predomi- 

 nance of the spiculous over the sarcodal element. Ex. gr. 

 Acarnus innominatus, in which the sarcodal element is re- 



