REPORT ON THE HEXACTINELLIDA. 321 



current canal spaces, and in every transverse section they may be observed to alternate 

 with tolerable regularity. 



The dermal skeleton consists of pentacts or hexacts with pronged terminal rays, and 

 in addition to these numerous scopula3 of different forms occur. 



The gastral skeleton consists of pentacts or hexacts, which exactly resemble the cor- 

 responding dermalia. It also contains in most cases scopulse like those which are found 

 in the outer skin. 



In addition to the parenchymal uncinates, numerous discohexasters occur, more 

 rarely oxyhexasters and sometimes also simple regular hexacts in variable numbers. 



1. Chonelasma lamella, n. sp. (Pis. LXXXVIL, LXXXVIIL). 



In the neighbourhood of the Kermadec Islands (Station 170a, lat. 29° 45' S., long. 

 178° 11' W., 630 fathoms), the trawl brought up some fragments of a plate about the 

 size of a little hand, from 5 to 10 mm. in thickness, and provided with attenuated, smooth, 

 irregularly undulating margins. They are in some places somewhat bent and irregularly 

 thickened, but on the whole they appear tolerably flat. The soft parts are well preserved. 

 The two lateral surfaces exhibit to the naked eye no noteworthy difl'erences. Both sides 

 are covered by a fine delicate porous skin, through which are seen the round openings of 

 the passages, which are about 1 mm. in width, and traverse the plate in alternately 

 opposite directions. The distribution of these transverse canals is not, indeed, quite 

 regular, yet the general arrangement of the rectangularly crossed longitudinal and 

 transverse rows cannot be mistaken. 



The two sides of the other macerated specimen are represented, from a photograph, 

 in their natural size, on PI. LXXXVIL figs. 1 and 2. They exhibit a slightly bent, but 

 otherwise smooth macerated plate of 3 "5 mm. in thickness, which was obtained at Station 

 148a (lat. 46° 53' S., long. 51° 52' E.), from a depth of 550 fathoms on hard ground, 

 while the skeletal fragment figured on PI. XC. figs. 9, 10, and 11, in natural size, 

 which was dredged at Station 56 (lat. 32° 8' 45" N., long. 64° 59' 35" W.), from a depth 

 of 1075 fathoms on Coral mud, appears to belong to the same species. 



The macerated dictyonal framework exhibits notable variations in the difi'erent 

 regions of the plate. While the beams in the neighbourhood of the two surfaces 

 form a tolerably narrow-meshed, and somewhat irregular framework, which surrounds 

 the wide round openings of the funnel-shaped transverse canals, the middle portion of 

 the plate exhibits a regular system of perfectly square or rectangular meshes (PI. 

 LXXXVIIL fig. 1). Since these rectangular meshes in the middle layer are much wider 

 than the meshes in the neighbourhood of the two bounding surfaces, and since the 

 middle framework consists of beams, which are not only longer but thinner than those on 

 the surfaces, it is easy to understand how this middle layer may readily break, and 



(ZOOL. CHALL. EXP. — PART LIU. 1887.) Ggg 41 



