ME. A. DENDY ON WEST-INDIAN CHALININE SPONGES. 365 



additional fibres is about 0013 millim. Towards the inner surface of the tube the 

 main skeleton becomes extremely irregular in its arrangement. 



A special dermal skeleton is, as usual, developed only on the outer surface of the 

 tube, where it consists of a polygonally-meshed reticulation of comparatively slender 

 fibre, averaging about 0*025 millim. in diameter, but varying considerably in this 

 respect. The fibre throughout is very pale and transparent. 



The species may be readily recognized by its very remarkable and characteristic 

 external form. As no satisfactory figure has yet been given of it, that of Duchassaing 

 and Michelotti being very poor, I have thought it desirable to take the present 

 opportunity of giving one. 



Locality. Bahamas. 



Spinosella maxima, n. sp. (Plate LXI.) 



There are two large specimens of this remarkable species in the collection and one 

 smaller one. The latter presents certain minor differences from the other two and 

 may be best regarded as a slight variety. 



The largest specimen is a great irregular mass, composed of about twenty tubes of 

 various shapes and sizes, all united together at the base and some also united laterally 

 at points of contact. Sometimes the tubes are constricted at the mouth, and sometimes 

 they are much expanded so as to become funnel-shaped. The wider ones are 

 commonly compressed. The largest orifice, which is much compressed, measures about 

 36 centim. in width, but this is formed by the lateral fusion of at least four different 

 tubes which have all a common orifice. The orifice of the smallest tube, on the other 

 hand, measures not quite 1 centim. in diameter. The total height of the entire 

 specimen is 45 centim. and the greatest breadth nearly 50 centim. 



The outer surface of the sponge is aculeated by extremely numerous, closely placed, 

 blunt, spinous processes, of various lengths up to about 1*25 centim. The margin of 

 the orifices is extremely thin and papyraceous and delicately veined in a dendritic 

 manner. The colour of the specimen, which is of course a mere skeleton, is pale 

 yellow and the texture is firm and hard but elastic. The true oscula are irregularly 

 scattered over the inner surfaces of the tubes. 



The main skeleton is composed of strong horny fibre, of very various diameter, com- 

 pletely destitute of spicules. The arrangement is very irregular, but one can distinguish 

 between a large-meshed reticulation of very stout fibres and very irregular meshes, and 

 a smaller-meshed reticulation of fine fibres which take their origin from the stouter 

 ones and also from an irregular network. The stouter fibres average about 012 millim. 

 in diameter, and the fine ones about 0-013 millim. 



On the outer surface of the tubes there is a well-developed dermal skeleton, composed 

 of a reticulation of stout horny fibres with comparatively small, rounded meshes. 

 Here, again, there are no spicules. 



vol. xii. — part x. No. 3. — April, 1890. 3 g 



