isops. 35 



regularly calyciform : in these, the peduncle, which is short and irregular, 

 measures 20-30 millim. in diameter and is about 40-50 millim. long. The 

 total height of the sponge varies from 100 to 180 millim. The margin of 

 the cup is narrow, sharp, and regularly circular, in a plane vertical to the 

 axis of the sponge. The mouth of the cup has a diameter of 40-50 millim,, 

 and the cup is 50-60 millim. deep ; irregularly conic. The thickness of the 

 cup-wall varies much, from 10 to 30 millim., in consequence of the irregu- 

 larities both of the inner and outer surface. The lamellar specimens attain a 

 length of 300 millim., and a thickness of 30-40 millim. The surface of the 

 cup-shaped specimens is rendered very uneven by numerous irregular out- 

 grou'ths and depressions, whilst the surface of the lamellar forms appears more 

 uniform and smooth. TJie surface has a rough, somewhat shagreen-like 

 appearance ; this is particularly well visible in di'ied s[)ecimens. A difference 

 in the degree of roughness of the outer and inner surfaces of cup-shaped 

 specimens, or the different sides of lamellar ones, can easily be discerned. 

 The oscula are found on one side of the lamellae only, and the oscular side 

 is the smoother one of the two. In the cup-shaped specimens the oscula are 

 confined to the inner surface of the cup. The oscula are circular, and mea- 

 sure 0-5-1 millim. in diameter. They are, on an average, 1-5 millim. apart : 

 more numerous m depressed portions of the surface than in others, and absent 

 near the margin. In spirit of a uniform melange colour ; dry, lighter brown, 

 yellowish in the interior. 



This sponge is generally inhabited by commensals, particularly tubicole 

 Annelids, the abodes of which are so similar to true sponge-canals that it 

 is difficult to recognize their true nature. Apart from these, our sponge does 

 not present any great peculiarities. The entochonpe are slender and small : the 

 ectochona) large and dome-shaped, about as wide as long, measuring 0-6 millim. 

 each way. The cortex is 0*8 millim. thick and of uniform structure through- 

 out. Below the outer surface tangential canals of the inhalant system 

 can be observed, most of these have a diameter of 0-1 millim., whilst a few 

 attain a width of 0-3-0-5 millim. Their transverse section is circular. 



Skeleton. — (1) Tetraxon Me(jasclera. Abundant just below the superficial 

 layer of globostellates. Scarce in the interior. Long ray always centripetal. 

 Angles between centripetal and tangential rays >90°. Centripetal differ- 

 entiated ray 1 X 0-025 millim., slightly conic, and abruptly but not sharp- 

 pointed. Tangential rays 0*26 x 0*02 millim., slightly curved, conic, not sharp- 

 pointed. — (2) Monaxon Mecjasdera. Forming a network in the interior, single 

 or in bundles of two or three series ; those below the cortex disposed radially : 

 0-8x0-016 millim.; slightly curved, and tapering abruptly to a sharp 

 point. — (3) Polyact Glohostellates, forming a hard cortex, 0-8 millim. thick ; 

 also found scattered in the interior of the sponge ; 0-048 millim. in dia- 

 meter, with a granular surface. Young stages, measuring 0*02 millim. in 



