PUNNETT—LAND-NEMERTEANS. 59 
middle line and by vestiges of two lateral stripes at either end of the worm (¢f. Pl. 11. 
fiz. 1). The large proboscis, when extruded, is of about one-half the body-length. 
The structure of the body-wall presents few features of special interest. The muscle- 
layers are somewhat poorly developed and the basement membrane is thin. Throughout 
the body cutis-glands are practically absent, except on the ventral surface in the region 
of the brain: here they are well developed, and over the area where they open to the 
exterior the basement membrane is much attenuated (cf. figs. 3 & 4). Connecting 
the openings of the two cerebral organs on the ventral surface is a very shallow eroove 
lined by aglandular ciliated epithelium, similar in appearance to that lining the ciliated 
canals of these organs. 
The cephalic glands are large and extend backwards past the brain into the region of 
the stomach (cf. figs. 2-5, gl.c.). The great development of these glands is characteristic 
of land-nemerteans, and is doubtless connected with the necessity of keeping the body- 
surface moist. The cutis-glands found in other groups are practically absent in the 
Metanemertea, and their place is taken by the greatly enlarged cephalic glands in these 
eases where a considerable amount of slime is necessary for the well-being of the worm. 
The small cesophagus opens into the rhynchodxeum immediately in front of the brain. 
The stomach is large, and on either side of it the first intestinal gut-pouch extends 
forwards. Neither gut-pouches nor stomach reach forward so far as the brain. 
The proboscis is large and contains 19 nerves in each of the three specimens 
examined. ‘Four reserve stylet-pouches are present. Unfortunately the stylets were in 
each case dissolved away. The proboscis-sheath extends to the extreme posterior end. 
In section, the muscles on the dorsal side of the sheath are here and there much swollen 
(cf. fig. 6), recalling the condition described by Bergendal for Callinera birgeri. In the 
present species the appearance is much less definite, varying irregularly with the 
individual and with the different regions of the body 
The worms are hermaphrodite. The testes are found between the nerve-cords, and the 
ovaries dorsal to them (c/. fig. 6). Each ovary, when fairly mature, contains a single 
large ovum. The yolk is apparently provided by the follicle-cells, which are enlarged on 
the intestinal side of the ovary and full of yolky material. With the syncytium formed 
by these cells, the ovum enters into communication by several wide protoplasmic bridges 
(fig. 7). Through these the yolky matter formed by the follicle-cells apparently flows 
into the ovum. The condition recalls the remarkable arrangement in Drepanophorus 
borealis *, where each follicle-cell elaborates yolky material and conveys it to the ovum 
by a spout-like process. A yolky thickening of the follicular layer was observed by 
Dendy in G. australiensis +, though he does not appear to have observed any direct 
communication between the cells of this layer and the ovum. In G. agricola, Coe ¢ 
has shown that the yolk is provided by absorbed ova instead of by the follicle-cells. 
Speaking generally, the follicle-cells would appear to become the active providers of 
yolk where the ova are exceptionally large. 
* Punnett, Proc. Zool. Soc. 1901, ii. p. 105. + Loe. cit. p. 548, 
+ Loc. cit. p. 114. 
g* 
