105 



desman. Maximum length iv,, 111 apex to apex -,(' branches about 074 millim., wit li 

 main axis about (HH! inilliin. thick. 



(2.) Stout and slender monaxonid spieules (Plate IV., li-. ... /- 0) j more or less 

 Clirscd ;uid variously ended, ran^in^ from o..e,,te to stron^ylot r .md styloto ; 

 :d,(,iil. I)-!)H millim. by (COIiC,!) millim., I ^ millims. by O'O'.Mi; millim., I 'UH niilliins. by 

 n-(i:!'JH inilliin., &C. ; very variable. 



The most, interesting I',.;,.),!!,-,, ,,f t,|,j M Hpongc, in the strong development ,,(' I lie 

 inonaxoiiid K|)i(;ul(!H (rhabdi), which, in three out of the four specimens (I lie f.inrl.h 



being dead aad infeeted by another pongo\ play an equal |.-nt \\ith the de.smas in 



Uie miii|>o.sitioii of th(! Hkohiton. Tbis ronditiou of t,b(! skelelun sii^estH that 

 certain Moim.xoiiellid Hjion^eN usually aHHor;ia,t,(!(| with the A xinrllid.-e m.-iy he derived 

 from Lit, hist, id ann-sl.orn by the wi|i|in!ssi<ui of the desnui.s, or I ha.l, cei 't;iin Lithist.ids 

 with monOOrepid desmaH may possibly be derived I'n.m Moiuixonellid uncostfU's. 



/'i'/roit,i,;i. iini.wtl.is is (ividently very closely nslated to TOI-SIONT'S /'. t/rini't/itii, the 

 ty]ie of the ircmiH, fro in t,he A/.oi'(. The |rinci|,;il did'eri'iice ;i|i|,ears to emirem 

 t'he orn;iiiie,nl;il,ion ,,(' the de.smas, which, in /'. i/riuntl<lii\ are orn; ..... -nted at tin- 

 extremities with littN; conie.aJ tubercles, not |n,inlei|. Th(e, are absent, or very feebly 

 developed in the (!e,ylon spec.ies, but subsequent, researches ma.y make it desirable In 

 unit,(^ the two. 



I'.!V. 1'J8 ; 210 (dead, and infested by another sponge; deep water outside pearl 

 banks, (iulf of Ma,naar) ; 257 (type) ; '20!) (yoiin^ ; deep ualer oil' < lalle ami on wards 

 up West ('oast of <!eylon). 



MONAXONIOIddDA. 



TetraXODlda in which the primitive, telra.xonid and let i -act inellid condition of the 

 ine^ascleres has been entirely lost and none but inona xonellid me-a: '! 

 remain. No desmaH are, developed. 



With the recognition of the trim nature of the monaxonellid sponger aH reduced 

 'I'el ra .xotiida, it, becomes once more (losirahle, to modify the name of the ^i-oup. 'I'he 

 old na.me, " Monad .iuellida-," which we, owe, to /I'rrKl,, was object iona hi 

 implying thai the spicnles are nooossarily monactinal (one rayed), ulule, as a mallei 

 of fact, they may b<; also diaelinaj (two-rayed ). Sol, I, AS therefore alten-d (he name 

 to " Mouaxonida'," which was afte.rwards aid-red to " Mona \onida." under which 

 name the group appears in the ' " < Jhallen^er " 1,'epoi ts ' and other recent \\orkfl. 



The name " Monaxonida," however, becomes distinctly object ionalile when used for 

 a mere subdivision of the order Tetraxonida, Contracted with the 'I'etract inellida ; 

 and I therefore propose to a^a.iu modify the na.ine of the ^ronp, choosing this time 

 the term " Mona ..xonellida," which is, I believe, both cmrect, in meaning and in 

 harmony with the scheme of classification adopted 



The Mona xonellida form, however, an uniialni.il ;'ioup of polyphyletic origin, 

 which we can only retain aw u ma.lt er of convenience until ue know moie about their 



P 



