﻿SPONGES.-HALLMANN. 20" 



According to its description this species possesses the external 

 structural characteristic of Echiyiodathria but differs from 

 the latter in respect to its echinating spicules, which are 

 spined, and in respect to its coring spicules, which appear to 

 be auxiliayy. It accordingly possesses the spiculation of Wil- 

 sonella, of which genus Plcctispu niay therefore be regarded 

 as a synonym. Lendenfeld himself, i shortly after his estab- 

 Ushment of this genus, recognised the necessity of restricting 

 the name to forms with acanthostyles and thereby tacitly 

 indicated the type-species. 



Genus Clathria, O. Schmiclt {cnifinl.). 

 The main skeleton is a reticulation of ivell-developed 

 horny fibres ivhich arc cored with smooth or, less fre- 

 quently, partly spined principal styli, and echinated by 

 spined or (rarely) smooth accessory styli. Auxiliary 

 monactinal or {rarely) diactinal megascleres of a single 

 kind, smooth or terminally spined and typically slenderer 

 than the principal styli, occur in the ground and dermal 

 tissues and occasionally also, though rarely in any con- 

 siderable number, 7vithi}i the fibres themselves ; they are 

 usually most abundant in the superficial tissues where 

 they may become so closely aggregated as to constitute a 

 definite dermal skeletofi. There are no special dermal 

 styli. Microscleres, when present, are typically isochelw 

 palmatcc or toxa. 



The above emended diagnosis is intended to exclude not 

 only such species as are referable to the genus Rhaphidophlus, 

 l)ut also a number of others which might conveniently be 

 united under Carter's genus IVilsonella {vide infra). At the 

 same time an attempt has also been made to render the 

 definition more precise in regard to the characters of the spi- 

 cules. It is, for instance, no longer correct to say that the 

 coring styli are smooth ; in many species they are basally 

 tipped with spines, whilst in Clathria clathrata, Whitelegge,2 

 they are provided with moderately large spines over a con- 

 siderable portion of the basal region and usually, in addition, 

 with extremely minute spines on the remaining portion of 

 their length. Neither is it any longer permissible in the face 

 of such species as C. transiens, sp. nov. to speak of the echin- 

 ating spicules as if they were invariably spined. If the genus 

 IVilsonella be accepted in the sense in which I define it, a 

 number of species which up till the present have been in- 

 cluded in Clathria will need to be removed from the jjenus. 



1 Lendenfeld— Monograph of the Horny Sponges, 1889, p. 99. 



2 Vid^ infra, p 209. 



