SILICIOUS AND HORNY SPONGES WILSON. 373 



/ound which very many of the spicules may be grouped), a slenderer 

 and a stouter, which, however, intergrade. The one type measures 

 about 5 mm. by 50 \i, the other 3 mm. by 100 \l. 



The common large promonaenes. prodiaenes, and the protriaenes 

 of the radial bundles do not differ from those of the type. 



The stout form of protriaene with cladome projecting beyond 

 the surface is present as in the type. A few were observed in which 

 one and even two clads were completely degenerate. 



The protriaenes of the marginal fringes possibly average a larger 

 size than in the type, clads of the larger ones observed ranging 

 from 180 to 280 y. in length. 



In this form, as said, root bundles are abundant. Long, stout 

 protriaenes with short clads are common in them. The rhabdome 

 is over 11 mm. long, about 36 \i thick above, clads 50-70 \i long, 

 20 (A thick at the base. 



The anatriaenes of the radial bundles are like those of the type. 

 They are common in this specimen. The anatriaenes of the root 

 bundles are like those present on the under surface of the type. 



The sigmas of the ectosome and interior show the same contrast 

 as in the type. The former are 28-44 p. long, the latter 16-20 y. long. 



Holotype.— €at. No. 21318, U.S.N.M. 



TETILLA (CINCHYRELLA) CRUSTATA, var. PATELLAE-SPINOSAE, new variety. 



Plate 39, fig. 7. 



Station D5335, 23 specimens. 



The shape is remarkably uniform. The sponges are subspheroidal 

 with a noticeably flattened basal surface; diameter in most of them 

 70-85 mm., but ranging down to 40 mm. The general surface is 

 smooth or nearly so, but examination shows that, as in the type, the 

 spicules of the radial bundles naturally project. Over the lower- 

 most part of the lateral surface just above the base, projecting 

 spicules are present in abundance in some of the specimens (doubt- 

 less rubbed off in others) ; they protrude downward and outward 

 a few millimeters. Over the basal surface, in all but one specimen, 

 the projecting (root) spicules have been for the most part rubbed 

 off. But in this one specimen the whole basal surface is covered 

 with a mat of root spicules, which holds a quantity of sand; the 

 mat is now only a few millimeters thick, doubtless compressed arti- 

 ficially. Density and color as in the type. 



The poriferous pits are numerous and resemble those of the type; 

 depth in two representative pits, 13 mm. and 20 mm. As in speci- 

 mens of the type which are high enough to have a considerable 

 area of lateral surface, the pits occur especially on the latero- 

 superior surface, much more rarely on the extreme upper part of 



