390 Mr. T. Iliggiu on tico IJexactineUid Spouges. 



Fi(j.2. Portion of dermal latticework, sliowinj; tlio relative position of 

 the spicules of which it is comuosed : a a a ti, arms of larjre 

 nail-like spicule ; sss, shafts of tlie same ; d, sarcode stretched 

 across the mesh ; p, pores ; c, feathered spicules (no. 6) in silu. 

 Dia^'rammatic. 



Fi(/. .'>. Sparsely spined acerate spicule, the spines pointing towards the 

 middle of the spicule. 



Fiff. 4. Crucial spicule, with points of amis barbed like a harpoon. 



Fi(/. o. Small se\radiate spicule, the arms spined towards their ex- 

 tremities ; the spines bent upon themselves, poiutiii<^ towai'ds 

 the ends of the arms. 



Fiff. C. Slender birotulatewith eifjrht arms at each end, the shaft studded 

 with short blunt spines throu^rhout its entire lenjrth. 



Fit/. 7. Minute birotulate <renerally with eight arms at each end, in yieat 

 quantities thniughout the sponge. 



Fiff. 8. Crucially headed plumose spicule of the latticework. 



Fig. 9. Free end of one of tlie spicules of the glass rope. 



Fiff. 10. Free end of one of the spicules of tlie glass rope of a Japanese 

 lltiahnevia, in the possession of the Liverpool Free Museum 

 (no. 10. 9, 08. 1). 



Plate XXII. 



Fiff. 1. Large acerate spicule fi-om surface of Ilyahtnema cebucnsf, similar 

 to tliat found in the stem of Cnitcroitiorji/ia Meffcri ; it is also 

 found in Hyalonema SiihoUUi, not, lutwever, on the surface, 

 but in the interior structure round the cord. It measures 

 about 4-12ths of an inch in length by 1-OOth in its broadest 

 part. 



tiff. '2. '• Spinicrucial " spicule fiom base of sponge-head oi Hyaloneina 

 cehtieiisc, in gi-eat quantitv about the cord ; length of each aim 

 4-oOOths to 5-oOOths of an inch. 



Fiff. 3. Litbaria hemispJufrica, Gray, after a photogi-aph by Robinson and 

 Thompson. 



Fit/. 3 A. Anchonng-spicnle oi Laharia hemisjihcerica, di'awn to the scale 

 of 1-oOOth to l-8th of an inch. 



Fiff. 4, Large nail-like spicule from the surface-reticuhitiou of the same. 

 Shaft A an inch in length, with a diameter of l-48th of an inch 

 at the head; length of arms i, 5, \, 5 inch respectively. 



Fiys. 5-7. Plumose spicules, extreme forms, there being many varieties 

 of intermediate shape ; measuring from i-oOUths to lO-oOOths 

 of an inch in height or length of plumose shaft. 



Fiffs. 8-14. Some of the spicules of the general structure : 8, 0, 10 measure 

 on an average 1-lOth of an inch in length; 11 is peculiar to 

 the species, and measures generally 8-oUOtlis of an inch in 

 length ; 12 and l."i are drawn to the scale, viz. l-jOOth to l-8th 

 of an inch (13 supposed to be an immature form of 12); 

 14 measures 3-oOOths of an inch from the point of one arm to 

 the point of the arm opposite. 



