THE SPONGES. IIG 



MONAXONIDA Ridley and Dendy. 



HADROMERINA Topsent. 



POLYMASTIDAE Topsent (1898). 



Polymastia Bowerbank. 



1864. Polymastia Bowerbank, 1864, p. 177. 



1887. PolymasUa Bwk., Vosmacr, 1887, p. 328. 



1887. " " Ridley and Dendy, 1887, p. 210. 



1896. " " Leudenfeld, 1896, p. 222. 



1896. " " Dendy, 1896, p. 249. 



1898. " " Topsent, 1898, p. 101. 



1900. " " Topsent, 1900, p. 131. 



Polymastia maeandria, sp. nov. 



Plate 16, Figs. 3, 4-65 Plate 31, Fig. 1. 



Diagnosis. Subspheroidal, firm, very light brown in color. Papillae in general low, 

 rounded, wart-like; oscular papillae longer. Entire surface appears smooth, although 

 covered with closely set bouquets of small tylostyles, 280 fj. x 12 fx. to 124 /x x 5 /4. Super- 

 ficial covering of projecting tylostyles interrupted by bare pore areas of irregular shape, 

 frequently long and meandering. Cortical layer of large spicules, 500 /j, thick; not 

 separated by a fibrous layer from the tylostyli of the surface bouquets ; spicules of the 

 layer for the most part tangential ; chief spicule a fusiform tylostyle 850 fx x 3S fito 7G5 /x, 

 X 32 fi. Skeletal bundles radiate from the interior to the surface ; chief spicule, a fusi- 

 form style 1580 fxx36 fxto 1020 fji x 28 fx. 



Station S40S, one specimen. 



Sponge body (Fig. 2, Plate 16) is subspheroidal, about 20 mm. in 

 diameter, attached by its under surface. In the neighborhood of the lower 

 margin the surface is without mammillary protuberances. Elsewhere 

 wart-like protuberances, not bearing oscula, are scattered over the .surface 

 at intervals of about 2 mm. Some are high enough to be hemispheroidal, 

 others much lower ; the width commonly about 2 mm., although ranging 

 from 1 to 3 mm. In addition, the upper surface bears near the centre 

 three oscular papillae, each with a terminal osculum which is nearly closed. 

 The papillae are hollow, conical, with rounded tips, 2 to 3 mm. high, and 

 about 3 mm. wide at the base. The thickness of the wall of the papilla 

 exceeds the diameter of the included canal. 



The whole surface, including the mammillary protuberances and oscular 

 papillae, is quite smooth to the eye and the touch. The color is a very 

 light brown, the surface lightest near the lower margin. The superficial 



