PLATE XV. 



Fig. 1. Gerebratulus longifissus, n. sp. Transverse section through the proboscidian sheath, a, the 

 inner longitudinal muscular layer of the body wall; pr.sn, the proboscidian sheath nerve; 

 Pr.S, the lumen of the proboscidian sheath; e, its inner epithelial lining; b, the homo- 

 geneous basement membrane of this epithelium, traversed by radial fibres and separating 

 the aforesaid epithelium from the muscular layers (an inner longitudinal, and an outer 

 circular) of the proboscidian sheath ; Gt, the gelatinous tissue between the proboscidian 

 sheath, the intestine and the body wall ; dv, the dorsal blood-vessel. 



Fig. 2. Gerebratulus inwrnr'-ii, n. sp. Transverse section of the proboscis, b, the ensheathing mem- 

 brane ; a and ■/, the two layers of longitudinal, y3', the layer of circular muscular fibres, the 

 latter connected crossways at two diametrically opposite points with the membrane b ; n.pl, the 

 nerve-plexus between /3' and y; E, the very high inner epithelium with smaller (c) and 

 larger (C) batteries of nematocysts. 



Fig. 3. ( 'erebratulus macroren, n. sp. Transverse section of the proboscis much further backwards ; 

 the proboscis is thinner, the muscular fibres (a) only longitudinal, the epithelium (E) 

 flattened, the nervous plexus replaced by two longitudinal nerve-stems N. 

 Gerebratulus angusticeps, n. sp. Head, a, from below ; b, side view. 

 Gerebratulus parkeri, n. sp. Head, a, side view ; b, from below. x l\. 

 Gerebratulus sp. inc. Two fragments from Japan. x 2. a, dorsal view ; b, ventral view. 

 Gerebratulus sp. inc. Transverse section of one of the fragments of fig. 6. /, the integu- 

 ment ; a, /3, and y, the much reduced muscular layers ; N, the lateral nerve-stems ; Int., the 

 intestinal canal and caeca, suspended in the gelatinous ground tissue Gt ; Gt', the same tissue 

 expanded between the very sparse external fibres of the muscular layer y ; PrS, the probos- 

 cidian sheath; bv, the blood-vessels. 



Fig. 8. Gerebratulus sp. inc. Lateral view of the head of another specimen from Japan (Kobe). 



Fig. 9. Gerebratulus longifissus, n. sp. Longitudinal section of the tail end. /, the integument ; 

 Lit, the intestinal epithelium ; a, /?, y, the muscular layers ; npl, the nerve plexus. This figure 

 is meant to show the general aspect of the muscular layer a, more highly magnified in fig. 10. 



Fig. 10. Gerebratulus longifissus, n. sp. The muscle-fibres of the layer a are seen to present a more con- 

 siderable diameter in successive vertical planes, forming rings round the intestine and alternating 

 with others in which this increase in diameter is not visible. Nuclei are also more numerous 

 in the former portions than in the latter ; Ep, the intestinal epithelium ; Gt, the gelatinous 

 tissue between this and the body musculature, with bundles of radial fibres. 



Fig. 11. Amphiporus moseleyi, n. sp. Transverse section of the lateral region with glandular cavities 

 ('//), arranged along the lateral line between the dorsal and ventral musculature a, piercing 

 the circular muscular layer /? at e, and suspended by the gelatinous tissue gt. I, integu- 

 ment ; B, basement membrane. 



Fig, 12. Amphiporus moseleyi, n. sp. One of the glandular caeca, more considerably magnified, with 

 granular epithelium and flattened nuclei exteriorly, the latter belonging to the surrounding 

 gelatinous tissue. 



Drepanqphorus lanlcesteri, n. sp. A section of similar glandular caeca in the dorso-median region 

 of the head. 



Amphiporus marioni, n. sp. A very unripe generative cascum, not yet opening to the exterior. 

 /3, Circular, a, longitudinal muscular layer. The caecum reaches down into the gelatinous 

 tissue, gt. 



Amphiporus marioni, n. sp. Ova in different stages of development. 



Gerebratulus parkeri, n. sp. An ovum. 



Drepanophorus snraticollis, Hubr. An ovum. 



Cerebratulus sp. inc. A batch of ova from a ripe generative csecurn of a specimen from Station 



321. The ova are surrounded by a hyaline membrane (which has erroneously been dotted 



by the lithographer) and pressed into polygonal shapes. 

 Fig. 19. Cerebratulus macroren, n. sp. Part of a transverse section, in outline. Prs, The cavity of the 



proboscidian sheath ; 7, integument ; y, /3, the muscular layers ; N, the longitudinal nerve-stem ; 



ge.c, the generative caecum ; o, its exterior opening. The duct to this opening, where it 



pierces the layer y, is considerably extended in bulk. 



Fig. 20. Amphiporus moseleyi, n. sp. A longitudinal section through the greater part of the compressed 

 oesophagus Oe, and subjacent intestinal casca (eo). 



