THE SPONGES. 91 



one or two concavities on the same side ; sometimes bent rather than 

 curved. The rays are tapering, most minutely roughened, and minutely 

 tylote. Total length of the spicule, 32-48 /x ; ray length, 10-20 fx. Sizes 

 close to a total length of 40 /x with ray length of 14 /ut, predominate. 

 The spicule is abundant in the parenchyma, dermal membrane, and espe- 

 cially abundant in the membranes of the pore areas. 



Sollas for the " Challenger " specimens gives total length of spiraster 

 39.5-47.4 fi, ray length, 12-19 /x. The spicules figured by Sollas (1888, 

 Plate VIIL, Figs. 7 and 8) might properly be designated metasters or 

 amphiasters, although Sollas says metasters are absent. 



Thenea fenestrata has hitherto only been recorded from the Atlantic 

 Ocean and Caribbean Sea. Schmidt's specimens were taken in Lat. 24° 

 36' N., Long. 80" 5' W., at a depth of 955 fathoms ; off Bequia at depths 

 of 1507 and 1591 fathoms. The "Challenger" specimens were taken in 

 Lat. 1° 47' N., Long. 24° 26' W., at a depth of 1850 fathoms; Lat. 10° 9'S., 

 Long. 35° 11' W., at a depth of 1715 fathoms. 



Thenea echinata, sp. nov. 



Plate \%, Figs. 1-9. 



Diagnosis. Body flattened but thick, and with a rounded polygonal outline. Eound 

 the periphery are several separate pore areas. An oscular depression near the centre of 

 the upper surface. Upper surface densely covered with radial oxeas, projecting 5 mm. 

 Under surface bears only small, short, projecting oxeas. Eoots evenly scattered over the 

 under surface. Megascleres : dichotriaenes, protriaenes, anatriaenes, oxeas. Microscleres : 

 spirasters; total length, 28-40 /x,; ray length, 10-14 fi. 



Station 341^5, 3 specimens. 



The body (Figs. 1, 9, Plate 12) is flattened, of a rounded polygonal 

 outline, and bears a number of peripheral pore-areas. About in the centre 

 of the upper surface is a smooth whitish (collenchymatous) oscular depres- 

 sion, into which open a number of efferent canals. This depression is nearly 

 round in one specimen, irregular in the others, and is without, or with only 

 a very indistinctly developed special spicular fringe. The upper surface is 

 densely covered with radially arranged long oxeas, projecting about 5.0 mm. 

 beyond, the surface, and holding much sediment. The under surface is 

 covered with radially arranged small oxeas, projecting about 1.0 mm. 

 Round the margin of the sponge the long spicules of the upper and the 

 short spicules of the under surface intergrade. Evenly scattered over 



