[DAWSON] FOSSIL STONGES AND OTHER ORGANIC REMAINS 



111 



The ('X!imi»lc's of lliis H|»ucit'8 wore pi-oluildy m-arlv i-yliiidrifiil tulios 

 from :{(» to fjM mm. in loriiflli, iinil alioul 12 mm. in width. Tlu' longi- 

 tudinal fascicles a !•(• alxtut 1 mm. iipart and tlu' transvcrsi' tiln-os from 1 

 to 2 mm, distant from <'a(di otlior. Tin- projectin<;- spiculai- rays (d' the 

 surfaci'H are only seen in these t'ompre.st;'_,l jpon^^es at the lateral mari;ins 

 a.s a sort (d' frinife. The five rays are somewliat thickly set ; they vary 

 from 5 mm. to 3 mm. in lenifth ; the lon<j:er I'orms in some instances occur 

 at re^'ular intervals, proiuihly at the angles of the mesh, and hetwi'en 

 these are the shorter rays. The extrenuties of many t)f the larifer foi-ms 

 jivo slif^htly swollen or cluh-Hhaped. Itut it is uncertain whetlior this is 

 an oriu;inal featui'e or is due to an irreifidai- di'position of the pvrltos 

 whi(di has now in all cases replaced the silica. 



This species appears as i-ihhand-liUe hands composcil of vertical and 

 parallel bundles of delicate spicules, with slender nansverse spicules 

 crosBin;j; them at intervals like the rounds of a lad<ler. It was |)rohal)ly 

 oi'i^inally cylindi'ical, hut the e.\t remit ii>s have not heeii seen, thouy;h 

 frannicn's nearly three inches in length have ]»cen found. One of its 

 most con.sj)ieuous eharactei-s is the possession of dense fringes of long 

 protective sjjicules at the sides, and these seem to he hased on a cortical 

 structure of crut(di-sha|)e(l or ci'uciform spicules, from which the defen- 

 sive spicules spri g. Scattered cruciform spicules of snudl size upoear 

 also in the middle of the i)an(ls. The fascicles of longitudinal spicules 

 ui-e sometimes loosely twisted in a spiral numner. Ilinde suggests that 

 in some of our sponges this appearance may he caused hy the accessory 

 threads, indicated hy Schulze as Comitalia} 



Sponges of the ahove species are sometimes associated with the 

 larger masses of Protospongia in such manner as to suggest a parasitic 

 or commen.sal relation ; hut this may he accidental, and may arise from 

 the cortical s])icules of Aciint/iodicfi/it hecoming entangled with the sur- 

 face of neiglihouring sponges. In one specimen 1 have the anchoring- 

 rods of ProtdSpotK/id tctranniui. with a patch of pj'rite inclosing some 

 of the spicules at the top and apparently attached to this, and rising 

 from it a specimen of Acauthodictya. This siiecimen certainly appears 

 to suggest a commensal relation. Another specimen is attached laterally 

 to the side of a fragment of Protospontjia, and another is very long and 

 much curved. 



It is possihle that some of the spirally twisted anchoring-rods men- 

 tioned helow may have helonged to this species, hut these have not V)een 

 seen attached, and there are only faint indications of simple or loosely 

 spiral roots. 



The genus, no doulit, approaches to Cyathophycus, but is separated 

 by its cylindrical form, tlie fascicled character of its longitudii al rods, 

 and its cortical spicidar arrangements. 



' Challenger Report, vol. xxi., page 17. 





