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



Elpidia willemoesi, but their number of rods amounts only to sixteen, eight towards each 

 opposite side. Two small ventral polian vesicles are found, they are of a sack-shaped 

 form, and measure about 5 mm. in length. The madreporic canal, which seems to 

 be destitute of deposits, pierces the dorsal perisoma and opens externally ; that part 

 of it which penetrates the body-wall is extremely fine. It is possible that traces 

 of calcareous deposits may be found where the canal enters the integument, though 

 I have not been able to detect them. In the individuals, examined by me, the 

 alimentary canal forms a small convolution posteriorly, and it does not seem impossible 

 that, when the body is extended to its full length, this may vanish so that the 

 digestive tract may have an almost straight antero-posterior course. The cloaca is incon- 

 siderable. All along both of the lateral nerve-cords are to be observed a number of 

 auditory vesicles, containing a varying number of otoliths. The reproductive organ 

 consists of two minute, thick fascicles of small cseca of the usual shape ; the common efferent 

 duct divides, when piercing the body-wall, into two narrow canals, which diverging 

 towards each opposite side within the perisoma, reach the dorsal ambulacra, where they 

 communicate with the exterior, each by a pore. 



Peniagone affinis, n. sp. (PL VIII. figs. 4, 5). 



Body elongated, of almost equal breadth throughout, three or four times as long as 

 broad, depressed posteriorly. Mouth anterior, ventral. Anus posterior, subdorsal. Ten- 

 tacles of almost ecpial size ; two ventral ones a little smaller than the others ; their dis- 

 coidal, terminal part with small, retractile processes. Pedicels about eleven all along each 

 side of the ventral surface. The dorsal surface with a broad, not very high, flat, trans- 

 verse lobe anteriorly with four projections on its upper margin, the middle ones being 

 considerably larger ; behind that lobe are two very small processes on each ambula- 

 crum. Integument rather thin and rough, with numerous crowded calcareous deposits, 

 composed of four more or less arcuated, slightly spinose, arms, and one to four 

 straight spinose processes, directed outwards ; the length of the arms and processes 

 extremely variable. 



Colour in alcohol, light grey, glassy. Length, about 100 mm. Breadth, about 

 27 mm. 



Habitat.— Station 147. December 30, 1873. Lat. 46° 16' S., long. 48° 27' E. 

 Depth, 1600 fathoms; bottom temperature, 0"8° C. ; globigerina ooze. Numerous 

 specimens. 



In spite of the great number of specimens which has been dredged from the above- 

 mentioned locality, only a few are in a tolerably uninjured state. The size is most vari- 

 able; the largest individual attains the above indicated dimensions, while the smallest has 

 a length of only 20 to 25 mm. and a breadth of about 7 mm. The body is almost equally 

 broad throughout or slightly widened posteriorly, its anterior and posterior ends being 



