PORIFERA OF THE L.M.B.C. DISTRICT. 201 



have acquired both large flagellated chambers aiid a rigid 

 siliceous skeleton. 



Chalina montcujui, Johnston. (PL XI., fig. 1.) 



Halichondria montagui, Jolinst., Brit. Sponges, p. 99, pi. vi. 



Chalina montagui, Boweib., B. S., vol. ii., ]). 366; vol. iii., pi. Ixviii. 



This species is an addition to the Fauna of our district. 

 I found it in a large and rocky tidal pool at Port Erin, 

 April, 1890. Johnston records it as " not uncommon in 

 the estuary of Kingsbridge at very low water, adhering to 

 stones, and is occasionally taken by the trawl in the open 

 sea on the coast of Devon, Conamara, and Dublin Bay." 

 Bowerbank adds to those localities Brighton and Hastings. 



The figure of the sponge, which I give in natural size 

 on PI. XL, was drawn by me from a photograph which 

 Dr. Kohn (Chemical Laboratories, University College, 

 Liverpool) had kindly taken from the specimen after it 

 had been in spirit for some time. The specimen is larger 

 than the one figured by Johnston, and differs from it in 

 having shorter and less whip-like tubular portions. Bower- 

 bank's figure had been taken from a rather poor specimen. 



The colour of the living specimen was straw-yellow. 

 The oscula are always placed on the extremity of conical 

 elevations, and measure 3 mm. in diameter. 



The spicules are mostly oxea, but a number of styli are 

 also present. Both kinds of spicules are slightly curved, 

 and measure on an average 0-096 by O'OOS mm. They are 

 imbedded either in ceratose or in the so-called ascending 

 fibres. Inside the ceratose the spicules are arranged in 

 unispicular row^s. The thickness of the ceratose fibre is 

 0-007 to 0-036 mm. The diameter of the ceratose meshes 

 varies from O'Oo to 0-1 mm. The ascending fibres extend 

 throughout the whole mass of the sponge, and give off 

 branches in all directions. Their diameter is 0-05 to 0-08 

 mm. Inside those ascending fibres the spicules are 



