EEPORT ON" THE MONAXONIDA. 29 



extremely soft and spongy, elastic, fibrous, tough. Surface granulated. Dermal 

 membrane thin and transparent, with fairly numerous, rather large pores. Oscula on 

 the top and lateral margins of the sponge. 



Skeleton. — Very well developed ; (a) Dermal ; a reticulation of spiculo-fibre supporting 

 the dermal membrane ; with irregular polygonal meshes and fibre varying in thickness. 

 (6) Main; a rectangularly-meshed reticulation of fairly stout spiculo-fibre in which 

 primary and secondary lines are readily distinguished, the ends of the primary fibres 

 commonly projecting for a short distance beyond the level of the dermal reticulation. 

 The primary fibres measure up to about 0"07 mm. thick, and the secondary fibres 

 are a little thinner ; in all the fibres the amount of silica bears no proportion to the 

 amount of horny matter, for the spicules, though polyseriaUy arranged, are of hair-like 

 thinness. 



Spicules. — Subcylindrical, or more or less abruptly pointed oxea, measuring only about 

 0-09 by 0-0014 mm. 



This species seems to come near to Chalina Jinitima, Schmidt, but the spicules are 

 very slender, and on the whole we have thought it best not to make an identification.^ 



Z:oca%.— Station 162, April 2, 1874; lat. 39° 10' 30" S., long. 146° 37' 0" E. ; 

 Bass Strait; depth, 38 fathoms; bottom, sand and shells. 



Genus Siphonochalina, Schmidt (Pis. VII., XLVL). 



1868. Sijplionochalina, Schmidt, Spong. d. Kiiste v. Algier, p. 7. 



1882. Tuhulodifjitus, Carter, Ann. and Mag. Nat. Hist., ser. 5, vol. ix. p. 367. 



Sponge tubular ; tubes smooth, both inside and out, usually narrow, each with a large 

 round opening at the summit. 



Schmidt's original diagnosis iloc. cit.) runs "Verzweigte oder unverzweigte Rohren. 

 Die Oberflaclie dicht, indem zwischen den wenig vorragenden Enden der radiaren Fasern 

 ein feineres, dichteres Fasernetz sicli ausbreitet." 



We have to distinguish between two genera of tubular Chalinine sponges, in the one 

 [Siiyhonochalina) the surface is smooth both inside and out, while in the other the outer 

 surface is beset with large, rugged, sj)inous processes ; for the second genus Vosmaer 

 has proposed the name Spinosella ^ in place of the old name Tuba, which was already 

 occupied. Schmidt's first described species of Siphonochalina is Siphonochalina coriacea 

 {loc. cit), which is shown by his figure (Taf. ii. fig. 4) to be one of the smooth forms. 



A very common feature in the genus is the marked annulation of the tubes, which 

 seems to indicate successive stages of growth. 



Unfortunately the genus Spinosella is unrepresented in the collection. 



1 Cf., however, RicUey, Zooh ColL H.M.S. "Alert," Brit. Mus., 1884, pp. 399, 604.; 



2 Bronn's Klass. u. Ordnung. des Thierreichs, Porifera, p. 342. 



