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



and very slender branches ; f, the madrcporic canal enveloped by the 

 same thick sheath of connective tissue, which surrounds the common duct 

 of the genital organs ; x, pores of the fine branches of the genital organs. 



Lcetmogone ivyville-thomsoni, Theel. 

 Fig. 7. Transverse section of a follicle of the male reproductive organs, showing a 

 series of longitudinal folds, a, epithelium ; b, circular muscular fibres ; c, 

 layer of connective tissue with the epithelial fining. 



Deima validum, The'el. 

 „ 8. Transverse section of a dorsal process, a, outer layer of connective tissue 

 covered with an epithelium ; b, inner layer of connective tissue ; m, nerve 

 fibres ; n, the large nerve branch ; o, inner covering. 



Scotoplanes robusta, n. sp. 

 ,, 9. One of the five pieces which compose the calcareous ring. 



Psychropotes longicauda, n. sp. 

 „ 10. Diagrammatic view of a transverse section of the large dorsal appendage ; 

 twice the natural size, a, the canals which communicate with the dorsal 

 ambulacra ; b, nerves ; c, connective tissue. 



Lcetmogone ivyville-thomsoni, Theel. 

 „ 11. The calcareous ring viewed from above and from behind ; twice the natural 

 size, x, the ambulacral canals and nerves. 



Scotoplanes papillosa, The'el. 

 „ 12. One of the five pieces which compose the calcareous ring. 



Oneiropkanta mutabilis, Theel. 

 ,, 13. View of a transverse section of a follicle of the female reproductive organs. 

 x, outer epithelium ; y, circular muscular fibres ; z, layer of connective 

 tissue ; a, inner epithelium ; b, ovisac ; c, germinal vesicle ; d, germinal 

 spot ; e, vitellus ; f, vitelline membrane. 



PLATE XXXVIII. 



Benthodytes abyssicola, n. sp. 

 Fig. 1. A small portion of the dorsal perisoma, seen from the outside, showing the 

 openings of the madreporic canal and of the reproductive organs. a, pores 

 of the madreporic canal ; b, genital pore. 

 „ 2. The same openings of another individual, a, the pore of the madreporic 

 canal ; b, the genital pore. 



