44 THE VOYAGE OF H.M.S. CHALLENGER. 



The ruaclreporic canal communicates with the exterior by a pore, situated a little 

 above the crown of tentacles ; it is invested by a thick sheath of connective tissue, 

 which increases gradually towards the body-wall. The individual which has been 

 at my disposal has lost the reproductive organ, except the efferent duct, which is 

 surrounded by the same sheath which encloses the madreporic canal. This common 

 efferent duct (PI. XXXVII. fig. 6) is very remarkable from its dividing into two short 

 and wide canals, which diverge towards the body-wall, where each divides into about 

 eight divergent long and very narrow canals ; those canals make some coils in the layer 

 of connective tissue of the body-wall before they reach the apertures by which they 

 open externally and which are placed far apart. Those secondary canals, carrying 

 sometimes one or two branches, diverge greatly from each other, and some of them 

 extend beyond the two dorsal ambulacra, consequently several of their openings lie in 

 the lateral interambulacra. 



Peniagone lugubris, n. sp. (PL X. fig. 1). 



Body elongated, three or four times as long as broad. Mouth anterior, ventral. Anus 

 posterior, subdorsal. The terminal part of the tentacles large, provided with small 

 retractile processes. Pedicels about five along each side of the ventral surface ; the 

 anterior third of the ventral surface destitute of pedicels. The dorsal surface with an 

 extension of the skin anteriorly constituting a very large, broad, transverse lobe, bearing 

 four rather small processes on its upper margin. Integument rather hard, with a great 

 number of crowded calcareous deposits, composed of a slightly elongated central part, 

 and two arcuated arms, diverging from each of its ends ; each arm with a large process, 

 directed outwards. 



Colour in alcohol, black-violet ; the ends of the tentacles almost black. Length, 

 about 70 or 75 mm. Breadth, about 15 or 20 mm. 



Habitat— Station 104. August 23, 1873. Lat. 2° 25' N., long. 20° 1' W. Depth, 

 2500 fathoms ; bottom temperature, 1"7° C. ; grey ooze. One incomplete specimen. 



The dorsal surface is convex, the ventral, on the contrary, almost flat. Anteriorly, 

 above the tentacles, where the body attains its greatest height, the dorsal surface is 

 provided with a very large, comparatively flat appendage, which measures in length 

 about 40 mm. The free end of this appendage is broad and slightly rounded, and its 

 base seems to be considerably broader than the body itself. This lobe, which has a 

 transverse position, crossing from one side of the body to the other, divides the dorsal 

 surface into a more or less horizontal, posterior part, and an anterior almost vertical 

 part. The appendage carrying four small, obtuse projections or processes on its upper 

 rounded margin, is traversed by four long and very wide canals tapering upwards, and 

 each of them entering one of the above-mentioned projections. As those canals are visible 

 to the naked eye through the walls of the lobe, the whole dorsal appendage gives the 



