SrONGIIDA. 621 



long, from those of tho latter in the greater relative stoutness of 

 the basal end and in their superior length (about twice that of 

 fenestratus). 



43. Leucophlceus fenestratus, var. (Plate LIII. fig. A.) 



See Part I., p. 464, of this Report. 



A spirit-specimen and some fragments, combining the external 

 characters (viz. erect, laminate, with the upper portion echinated 

 by fine upwardly directed processes, and with smooth, thick basal 

 portion) of Leucophlceus proteus, mihi, with a spiculation of the 

 character of L. fenestratus. The outward form of these two species 

 is, however, essentially the same, and the differences observed in 

 this point are mainly individual. The present specimen, linking 

 the Australian to the more western form, has decided a doubt which 

 I had as to the rightful position of the former species in the genus. 

 The specimen is young, measuring 5o niillim. (2 inches) in height by 

 (including a fragment which appears to belong to it) 35 millim. in 

 greatest diameter (that of the base). It consists of a massive basal 

 portion, enclosing a large quantity of calcareous matter (JNullipore, 

 &c), and of a slender flattened expansion, 20 millim. high, 10 millim. 

 broad, 4 millim. thick, arising from it ; the base is glabrous, the sur- 

 face being formed by a thin, transparent membrane, loosely attached. 

 Main skeleton consisting of compact spiculo-fibres about 10 spicules 

 broad, and of broad expansions containing a large number of spicules 

 loosely aggregated. There is no sign of horny uniting substance. 

 Spicules tapering gradually from near the centre, or about mid- 

 way between the centre and base, to a smaller rounded basal ex- 

 tremity, which is about one half the maximum diameter of the 

 spicule ; spicule tapering rapidly to moderately sharp point from two 

 or three diameters from apex; size of spicule -8 to 1-1 millim. bv 

 ■02 to -032 millim. (a considerable range for only two or three speci- 

 mens). The spicule has thus practically the same form as in both 

 the Australian varieties, and in its range of dimensions connects the 

 two. The colour, which is purple, as in L. proteus, but pale, is 

 possibly derived from some purple sponges which had' been kept in 

 the same vessel. 



Hah. Providence Eeef, Mascarene group, 24 fms. 



SUBEBJTID^E. 



The few species received illustrate well the wide affinities of 

 Sponges from this district. Tethya, s. str., which was not found on 

 the northern and eastern coasts of Australia, but which is recorded 

 by Bowerbank from the west coa.>t, appears here also, in the shape 

 of a species described by Bowerbank from Freemantle. Of the two 

 new species of Spirastrella, S. transitoria appears to throw fresh 

 light on the homologies of the spinispirular spicule. The Vioa 

 is identical with a Mediterranean species. 



