BY E. F. KALLMANN. 667 



varieties are practically the same. As seen in a vertical median 

 section of the sponge, cut in a direction perpendicular to the 

 lamellae, the skeleton appears as if consisting of parallell}'- 

 arranged, stout plumose columns of spicules, which in the 

 marginal region of the sponge aie nearly or quite separate from 

 one another(Pl. xli., figs. 1,2); these columns represent, of course, 

 transverse sections of the lamellse. The appearance of the 

 skeleton (of a lamella) in a direction at right angles to the pre- 

 ceding is shown in PI. xli., fig. 3. 



Mf^yascleres.— (i.) The oxea of the skeleton-reticulation are 

 curved, fusiform, regularly sharp-pointed spicules, langing from 

 550 to 770/x in length and up to 35//, in stoutness; individuals 

 less than 8/x in diameter are very rare, and those forming the 

 fibres very seldom are much less than 20/ji. Occasional spicules 

 are styli or substrongyla. 



(ii.) Long interstitial megascleres are exceedingly rare, and 

 appear to be invariably styli. The few observed measured from 

 950 to 1100/x in length and from 15 to 25/ji in stoutness. 



(iii.) Megascleres corresponding to the slender deinial spicules 

 of tlie preceding variety are apparently wanting. 



Microscleres. — The acanthoxea are exactly similar in form and 

 size to those of the preceding variety, excepting that their 

 minimal length is somewhat greater (about GO/x) and a consider- 

 able proportion of them (amounting to al>out 50%) exhibit a 

 bulbous dilatation. 



For Postscript, see p. 67 3. 



REFERENCE LIST OF LITERATURE. 



1. BowERBANK, J. S. — "A Monograph of the Briti.sh Spongiada?. " Vols. 



1-3; Vol. 4, edited, with additions, by the Rev. A. M. Norman. 

 Ray Society, London, 1864, 1866, 1874, 1882. 



2. Carter, H. J. — "Contributions to our Knowledge of the Spongida." 



Ann. Mag. Nat. Hist., (.">), iii., 1879, pp.284-.S(J4, 343-360. 

 3. "Report on Specimens dredged up from the (4ulf of 



Manaar. Part viii. Spongida." Op. cit., (5), vi., 1889, pp.3r)-61, 



129-156. 

 4. "Contributions to our Knowledge of the Spongida." 



Op. cit., (5), xii., pp.308-.329. 



