Sponges from South Australia. 287 



processes, which are v^erj long comparativelj, are united 

 laterally throughout into a fan-shaped form, rising from a 

 single stem, the large circular vents being arranged serially 

 on the margin. Largest specimen about 8 in. high b j 8 x 1 

 in. horizontally. Colour, when fresh, " bufF-grey." 

 Depth 20 fath. 



Group 9. BlVALVATA. 



Cavochalina hilamellata^ Lam. 



Stipitate, placentiform, doubled up like a bivalved shell 

 with a stem, i. e. vasiform compressed ; infundibular below 

 as the head approaches the stem, which is long and hard, 

 ending in a root-like expansion, expanding, in the contrary 

 direction, into a flabelliform bilamellar head above. Con- 

 sistence leathery. Colour, when fresh, " pale pinkish brown," 

 now mouse-brown. Surface externally wrinkled, rugosely 

 reticulated in high relief, nodose ; inside even, smooth, con- 

 centrically lineated. Vents small, scattered over the inner 

 surface. Structure compact, fine, composed of short-jointed 

 keratose fibre, scantily charged with the usual form of small 

 spicule, viz. acerate, smooth, curved, fusiform, sharp-pointed, 

 about 14 by |-6000ths in. in its greatest dimensions. Size 

 very variable, apparently increasing with the age of the 

 specimen ; the largest, of which there are several dry, but only 

 one wet specimen, about a foot each way, including the stem, 

 which may be 3 or 4 in. long, with a thickness of the head 

 towards the stem about one inch where the nodular excrescences 

 are most prominent, becoming gradually thinner in the oppo- 

 site direction, that is towards the border, where the nodular 

 processes ceasing leave a narrow smooth strip about one 

 sixth of an inch in thickness. 



Depth 19 fath. 



Hob. Marine. 



Loc. Port Phillip Heads, south coast of Australia. 



Ohs. This seems to me to be the species briefly described 

 by Lamarck (1st ed. t, ii. p. 366, no. 61), so I have given 

 it his designation. There are several dry specimens in Mr. 

 Wilson's collection, but only one wet one. From the great 

 number which I have seen it must be very plentiful under all 

 forms on the south coast of Australia, but all modifications of 

 that above mentioned ; whilst its leathery imperishable nature 

 and great toughness arising from the quantity of keratine in 

 the composition of its fibre, scanty and small spiculation, and 

 compact structure, render it as durable almost as the sole of 

 a shoe. It is subject to considerable variety in form, being 



20* 



