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Show 32 MR. W. F. LAXCHESTER OX THE [Jan. 17, Loc. British East Africa, 10 fathoms; 2 specimens, small. Chwaka, Zanzibar; 2 specimens, large. These individuals evidently correspond with a form described by Selenka from the Bed Sea, which differed from the type in the following particulars : the papillae on the hind end were a little shorter and thicker, the hooks a little shorter, and the ventral retractors tending to be inserted a little more posteriorly. Selenka was unwilling to establish a variety on a single specimen, but it would seem better, now that we have these additions, to distinguish the form as a variety. The papillae on the introvert are exactly similar to those on the hind end of the body ; but even shorter and broader. I figure these, and one of the hooks (v. figs. 2 ci, 2 b). 12. P hascolosoma g l a u c u m , sp. nov. (Plate I. fig. 3.) Loc. Zanzibar Channel, 10-15 fathoms. In this species, which is represented by a single specimen, there are no hooks, and only two retractors. The muscle-layers are so loosely attached to the skin that they readily tear away from it on opening the animal; the retractors themselves arise, as strands obviously split off from the longitudinal layer of the muscle-system, from the anterior border of the hinder quarter of the body, and meet each other round the oesophagus at the level of the base of the introvert. The body is 13 mm. (approximately) in length, the introvert 5 mm. only ; the latter has a slightly darker tinge, owing to the crowding together of the pigmented papillate bodies, which are very low and not visible to the unaided eye, but distinctly so with the lens, under which they appear as distinct black spots. The papilla? on the body are visible under the lens as distinct clear spots; under the microscope they appear as elongated bodies with a clear apical opening and carried on fields roughly oblong in shape. Internally, we find the oesophagus running back with the retractors as far as their insertion, and then bending sharply forward for a little distance before entering the intestine ; the latter contains about 16 spiral turns, and is not attached to the hind end of the body. The rectum is without a diverticulum, and opens by the anus just behind the level of the base of the introvert. Two muscle-strands support the intestine anteriorly, and two more, arising from close to the nerve-cord on each side of it, support the oesophagus at the angle where it bends forward. There is a contractile vessel, thickly beset with little diverticula, along the length of the oesophagus where it lies between the retractors. The neplnidia are colourless, and open just in front of the level of the anus. 13. P hascolosoma w a s in i , sp. nov. (Plate I. fig. 4.) Loc. Wasin, British East Africa; 10 fathoms. Six specimens, of which the largest is 15 mm. in length. The most characteristic feature of this species is the numerous rows of |