22 R. KiRKPATKiCK : A Nezv Dictyoniiie Sponge. [Vol. W , 



(fig. I), from Station 321, Lat. 5° 4' 8I" N., Long. 80° 22' E., 660 

 fathoms. 



Of the seven specimens the best preserved is the broken one (B) 

 depicted in fig. 2, in which many of the fiesli spicules still remain, 

 but neither in this nor the others are there an}^ traces of the 

 spicules of the dermal or gastral layers. 



The other specimens consist only of the dictyonal network ; 

 and the central tube is mostly filled with mud. 



In the longest specimen (A, fig. i) the central sub-cylindrical 

 column is 17 cm. in length, 1*4 cm. in diameter near the base, 

 and I cm. in diameter at the upper end. The specimen rises 

 from a solid disk-like base 3 cm. in diameter. In three of the smaller 

 specimens the basal disk is perforated b}^ an opening leading into 

 the axial gastral cavit}^ The thickness of the wall of the central 

 column varies from i"i to i'2 mm. In the inner wall are four 

 vertical rows of orifices leading to the lamellate branches. 



In several of the specimens the lumen of the central tube is 

 filled with mud ; in one instance there are several minute Ophiurids. 

 In five of the specimens the inner wall is smooth and the lumen 

 bare of structure. The upper end of the central cylinder opens hy 

 an oval orifice with the long axis forming angles of 50° and 130° 

 with the axis of the lamellar pair immediateh' below, and with the 

 margins slightl}' flared out. In specimen A is an incomplete (?) 

 vertical partition of slender dictyonal network, so that there is an 

 appearance of a double tube. The presence of mud makes it 

 difficult to discover whether the partition is complete or not ; 

 possibl}' at first there is a complete partition which becomes 

 ruptured as the sponge grows. In specimen B there are, on the 

 inner wall, alternating pairs of longitudinal vertical ridges situated 

 on a level with the orifices leading to the branches and in a 

 plane at right angles to them. 



The lamellate branches or lamellcs — 



The lamellae are arranged at right angles to the central tubu- 

 lar axis, and in opposite pairs, each pair forming angles of 50° and 

 130" with the pair above or below it, the open or obtuse angle of 

 the X thus formed (fig. 8) being 130° and the acute angle 50°. 

 A iDotanical colleague informs me that the four rows are 

 orthostichous, and that the arrangement in opposite pairs 

 alternately crossing, but not at right angles might be described as 

 spuriously decussate. Looking down on the specimen from above, 

 the wall of the central tube is visible along the course of the opposite 

 obtuse angles, but is concealed by the overlapping lamellae along 

 the line of the acute angles. Again, viewed in front there is an 

 appearance of bilateral symmetry, i.e., of two series of alternat- 

 ing lamellae on each side of the spaces bounded by the opposite 

 obtuse angles ; but the branches or lamelke develop in opposite 

 pairs, accordingly the bilateral S3aiimetry is a secondary develop- 

 ment. 



